NORTH HILLS SCHOOL AND COLLEGE Senior Boy’s Section (Branch: 2) PHYSICS NOTES th
10 CLASS
Written by: Zahoor Ahmad M.Sc. Physics Physics Islamia University University Peshawar Peshawar Reviewed by: by: Shahid Khan M.Sc. Physics University of Peshawar
Charsadda Road Near Faqir Abad Police Station Peshawar Contact NO: 0300-91709 0300-91709! !
“Education is not the learning of facts, but the training of mind to think.”
Charsadda Road Near Faqir Abad Police Station Peshawar Contact NO: 0300-91709 0300-91709! !
“Education is not the learning of facts, but the training of mind to think.”
Charsadda Road Near Faqir Abad Police Station Peshawar Contact NO: 0300-91709 0300-91709! !
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
3 NORTH NORTH HILLS SCHOOL COLL!"!
Si"#le $ar"onic %otion and &a'es Motion:
& o*y is sai* to e in +otion i, it chan-es its position .ith respect to its s/rro/n*in- or ea+pe4 o.in- .in*5 rotatin- ,an5 6iratin- pen*//+5 the +otion o, a car on a strai-ht roa* etc Types of motion:
There are three types o, +otion .hich are as ,oo.s 1 Transa ransator tory y +otion +otion 2 Rotat otator ory y +oti +otion on 3 Osciator Osciatory y or 7irato 7iratory ry +otion8 +otion8 Osciatio Osciation n Oscillation /Oscillatory /Oscillatory motion :
& o*y is sai* to e in osciation .hen it per,or+s to an* ,ro +otion ao/t its +ean position or e!ample:
1 The +otion +otion o, si+p si+pe e pen* pen*//+ //+ 2 The +oti +otion on o, +ass +ass9sp 9sprinrin- syst syste+ e+ 3 The +otion +otion o, stee stee strip strip e* e* in a oc; oc; "eriodic motion:
&ny +otion that repeats itse, in e
1 The secon* secon* han* o, o, a .atch .atch repeats repeats its +otion +otion on the the *ia in in e6ery one one +in/te 2 The earth earth co+petes co+petes its perio*ic perio*ic rotat rotation ion in e6ery e6ery t.enty ,o/r ,o/r ho/rs 3 The +otion +otion o, o, si+p si+pe e pen*/ pen*//+ /+ = The +oti +otion on o, +ass9 +ass9 sprinsprin- syst syste+ e+ The si+pest perio*ic 6iratory +otion +otion is cae* si+pe har+onic +otion +otion #imple harmonic motion:
Si+pe har+onic har+onic +otion +otion is the type o, 6iratory 6iratory +otion +otion in .hich the acce accee era rati tion on pro* pro*/c /ce* e* is *ire *irect cty y prop propor orti tion ona a to the the *isp *ispac ace+ e+ent ent ,ro+ ,ro+ the the e
a
∝ −
$. Motion of mass attached to spring:
Consi*er a o*y o, +ass >+’ attache* .ith one en* o, the sprin- pace* on a s+ooth an* hori?onta ,rictioness s/r,ace .hie its other en* is attache* to a e* s/pport as sho.n in the -/re I, an eterna ,orce @A is appie* on the o*y o *y an* it is *ispace* ,ro+ its +ean position @OA to.ar*s etre+e position @&A y co6erin- certain *ispace+ent @A
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
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&ccor*in- to Hoo;e’s a. .e ha6e
" ∝
⇒ " = ! #here >;’ is constant constant o, proportionait proportionaity y .hich is ;no.n as sprin-’s sprin-’s constant constant &,ter re+o6in- the eterna ,orce5 the +ass +o6es ac; to.ar*s the e
position >O’ /n*er the action o, restorin- ,orce@
A5 /t *oes not stop at point >O’ A/
*/e to inertia an* -oes to the ne. etre+e position > ’ The restorin- ,orce is e
⇒ " res
= − " = − ! − − − − − 1
&so .e ;no. ,ro+ Ne.ton’s secon* a.
" = m a − − − − − 2 /ttin- e
= − !
ma
⇒
a=
−
! m
⇒ a = constant (− ) ⇒
a
∴
! m
= constant
∝ − − − − − − −3
!
=
2π
m !
#OME %M"O&T'(T TE&M#: $. )ibra )ib ratio tion: n:
One co+pete ro/n* trip co6ere* y a o*y is ;no.n as one 6iration In the -i6en -/re it is the +otion o, +ass >+’ ,ro+ O to & then ,ro+ & to &’ an* then ac; to O *. Time period+T perio d+T:: The ti+e re
$o of vibrations t
In SI /nit5 the /nit o, ,re,’ an* ti+e perio* T are reate* y the e
1 T
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
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re’ Its /nit is +eter (+) 1. 'mpli 'mp litud tude: e: The +ai+/+ *ispace+ent co6ere* y a 6iratin- o*y ,ro+ either si*e o, the e+’
#imple pendulum:
& si+pe si+pe pen*//+ pen*//+ consists consists o, a s+a +ass (o) s/spen*e* s/spen*e* y a .ei-htess an* inetensie strin- (threa*) ,ro+ a e* s/pport as sho.n in the -/re I, .e *ispace *ispace the o ,ro+ its +ean position position >O’ to etre+e etre+e position position >&’ thro/-h a s+a *ispace+ent >’ an* reease it It .i +o6e to.ar*s >O’ /n*er the action o, -ra6ity There are t.o ,orces actin- on the o one its .ei-ht >#’ actin- *o.n.ar* an* secon* tension >T’ in the strin- actinactin - /p.ar*
The .ei-ht ,orce can e reso6e* into t.o rectan-/ar co+ponents θ
The co+ponent +- cos aances the tension in the strin- .hie the θ
co+ponent +- sin is a.ays *irecte* to.ar*s the +ean position >O’5 .hich pro*/ces osciations o, pen*//+
#hen the o is reease* ,ro+ point >&’ the eDecti6e co+ponent o, .ei-ht pro*/ces acceeration acceeration to.ar*s the +ean +ean position >O’ On the .ay ,ro+ >&’ to >O’5 the acceeration *ecreases -ra*/ay an* eco+es eO’ The o *oes not stop at point >O’ */e to inertia an* +o6es to.ar*s >& 8’ .ith *ecreasin6eocity 6eocity an* increasinincreasin- acceeratio acceeration n This process is repeate* repeate* a-ain an* a-ain an* 8 the o contin/es to osciate et.een >&’ an* >& ’ ro+ ro+ ao6e ao6e *isc/s *isc/ssio sion n it is cear cear that that in si+pe si+pe pen*//+ pen*//+ the accee acceerat ration ion is *irect *irecty y proport proportion iona a to the *ispa *ispace+ ce+ent ent an* a.ays a.ays *irect *irecte* e* to.ar*s the +ean position There,ore the +otion o, si+pe pen*//+ is si+pe har+onic +otion Mathematical Mathematical form:
Net ,orce actin- on the o
= W sin sin θ = − m % sin sin θ − − − − − −1
" net " net
∴ W = m % " net
&s .e ;no. ,ro+ Ne.ton’s secon* a.
= − m % sin sin θ = − % sin sin θ − − − − − 2
ma
⇒a
=
ma
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
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ro+ the -/re .e ha6e sin sin θ
=
−−−−−−−3
/ttin- e
= − %
⇒a=
%
(− )
⇒ a = constant (− ) ⇒ a ∝ − − − − − − − − −4
2haracteristics 2haracteristics of simple harmonic motion:
1 In si+pe har+oni har+onic c +otion5 +otion5 a o*y oscia osciates tes ao/t the the +ean position position O O 2 & res resto tori rinn- ,or ,orce ce res actin- on the o*y is a.ays *irecte* to.ar*s the +ean position O 3 The acce cceer erat atio ion n pro* pro*/c /ce* e* */e */e to the the resto estori rinn- ,orce orce res is *irect *irecty y propor proportio tiona na to the *ispa *ispace+ ce+ent ent an* a.ays a.ays *irect *irecte* e* to.ar* to.ar*ss the +ean +ean position O = The 6eoci 6eocity ty o, the o*y is +ai+/+ +ai+/+ at the +ean +ean position position O an* -ra*/a -ra*/ay y *ecreases as the o*y +o6es a.ay ,ro+ O &t the etre+e positions >&’ an* >&8’ the 6eocity o, SHO eco+es eco+es ?ero &t the +ean +ean position position55 the F! o, SHO is +ai+/ +ai+/+ + .hie its ! ! is e&’ an* an* >& 8’5 the ! o, SHO is +ai+/+ .hie its F! is e
The type o, 6iration8 osciation in .hich the a+pit/*e -ra*/ay *ecreases .ith ti+e is cae* *a+pe* 6iration8 *a+pe* osciation or e!ample:
#hen si+pe pen*//+ is *ist/re* ,ro+ its +ean position an* e,t aone5 the a+pit/*e o, 6iration *ecreases .ith ti+e an* e6ent/ay stops */e to the air resistance These osciations are cae* *a+pe* osciations
4a3e:
The *ist/rance *ist/rance that tra6es tra6es thro/-h thro/-h +atter +atter an* space an* trans,er trans,er ener-y ,ro+ one pace to another is ;no.n as .a6e 4a3e motion:
The trans+ission o, ener-y in a +e*i/+ */e to the osciatory +otion o, the partias o, the +e*i/+ ao/t the +ean positions is cae* .a6e +otion "ropagation of 5a3es:
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
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#hene6er a o*y 6irates5 it *oes .or; on the partices o, the +e*i/+ an* sets the+ into osciatory +otion These partices set the nei-horin- partices into +otion y trans,errin- the+ so+e o, its ener-y In this .ay the *ist/rance tra6es thro/-h the +e*i/+ /t partices o, the +e*i/+ 6irates ocay an* *oes not +o6e .ith the .a6e 2haracteristics 5a3e parameters:
The
The *istance et.een t.o consec/ti6e crests or tro/-h is cae* .a6een-th an* is *enote* y It is +eas/re* in +eters *. 'mplitude:
The +ai+/+ *ispace+ent o, the partices o, the +e*i/+ ,ro+ its ori-ina position is cae* a+pit/*e o, the .a6e -. reuency:
The n/+er o, .a6es passin- thro/-h a e* point in one secon* is cae* ,re ( ’ Its /nit in SI is hert? *enote* y H? . Time period:
The ti+e reT’ Its /nit in SI is secon* 1. )elocity of 5a3e:
The *istance tra6ee* y a .a6e in /nit ti+e is cae* 6eocity o, .a6e It is represente* y >7’ %athe"aticall) : velocity
=
$istanc t!a"##$
⇒
=
s
v
tim
t
#here>s’ is the *istance tra6ee* y the .a6e an* >t’ is the ti+e ta;en
&elationship bet5een the 3elocity, freuency and 5a3elength of a 5a3e:
&s .e ;no. ,ro+ the 6eocity o, the .a6e velocity
=
v
=
$istanc t!a"##$ tim
s t
#e aso ;no. that a .a6e tra6es a *istance o, >’ in ti+e perio* >T’ There,ore the ao6e e
=
λ #
=
1
#
× λ
f =
#e ;no. that ,re
=
1 #
p/ttin- in ao6e
f λ
ro+ ao6e e
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4a3e:
The *ist/rance that tra6es thro/-h +atter an* space an* trans,er ener-y ,ro+ one pace to another is ;no.n as .a6e 4a3e motion:
The trans+ission o, ener-y in a +e*i/+ */e to the osciatory +otion o, the partices o, the +e*i/+ ao/t their +ean position is cae* .a6e +otion The .a6es .hich re
Modes of transfer of energy:
The ener-y can e trans,erre* ,ro+ one pace to another y the ,oo.in- three +etho*s 1 'otion o, a +acroscopic o*y +otion
2 artice trans+ission
3 #a6e
$. Motion of a microscopic body:
In this +etho*5 ener-y is trans,erre* ,ro+ one pace to another */e to the co+pete +otion o, +acroscopic o*ies ,ro+ one pace to another or ea+pe: ener-y carrie* y +o6in- tr/c;5 ener-y carrie* y a proJecte* stone5 ener-y carrie* y .in*s5 a /et re* 5 .ater ,a5 ocean ti*es etc *. "article transmission:
In this +etho*5 ener-y is trans,erre* */e to coision or +otion o, +icroscopic partices or ea+pe: trans,er o, eectric ener-y5 con*/ction o, heat thro/-h a +eta ar etc -. 4a3e motion:
In this +etho*5 ener-y is trans,erre* ,ro+ one pace to another y +eans o, .a6es or ea+pe: so/n* ener-y co+in- ,ro+ a e5 i-ht ener-y an* heat ener-y co+in- ,ro+ the s/n The partices o, the +e*i/+ *o not +o6e ,ro+ one pace to another /t they ony 6irate ocay Mechanical 5a3es:
The .a6es .hich re
There are t.o types o, +echanica .a6es ase* on the +otion o, partice o, the +e*i/+ .ith the *irection o, propa-ation o, .a6e
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
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1 Trans6erse .a6es
2 Lon-it/*ina .a6es
$. Trans3erse 5a3es:
The .a6es in .hich the 6iration o, the in*i6i*/a partices o, the +e*i/+ is perpen*ic/ar to the *irection o, propa-ation o, .a6es are cae* trans6erse .a6es E!planation:
In trans6erse .a6es5 the partices osciate at ri-ht an-es to the *irection o, propa-ation o, .a6e ,or ea+pe4 the .a6es pro*/ce* in a stretche* strin- /p an* *o.n are trans6erse .a6es eca/se the *iDerent parts o, the strin- 6irate perpen*ic/ar to the *irection o, propa-ation o, .a6es The .a6e pattern o, trans6erse .a6es is sho.n in the -/re
Si+iary the .a6es pro*/ce* in a sin;y sprin-5 .hose one si*e is attache* to a e* s/pport an* the other si*e is +o6e* /p an* *o.n Trans6erse .a6es are pro*/ce* The part o, the .a6e .here partices are ao6e the +ean position is cae* crest .hie the part o, the .a6e .here the partices o, the +e*i/+ are eo. the +ean position is cae* tro/-h *. 6ongitudinal 5a3es:
The .a6es in .hich the partices o, the +e*i/+ 6irate ao/t their +ean position parae to the *irection o, propa-ation o, .a6es are cae* co+pressiona .a6es E!planation:
So/n* .a6es are co+pressiona .a6es5 in .hich the air +oec/es are *ispace* ,or.ar* an* ac;.ar* on the sa+e ais aon- .hich the so/n* tra6es Si+iary co+pressiona .a6es are aso pro*/ce* in the sprin- as sho.n in the -/re In co+pressiona .a6es5 the *enser part o, the .a6e is cae* co+pression .hie the ess *ense part is cae* rare ,riction
0i7erence bet5een
trans6erse .a6es an* on-it/*ina .a6es:
0i7erence bet5een trans3erse 5a3es and longitudinal 5a3es
1
Trans3erse 5a3es
6ongitudinal 5a3es
In trans6erse .a6es5 the partices o, the +e*i/+ 6irate perpen*ic/ar to the *irection o, propa-ation o, .a6e
In on-it/*ina .a6es5 the partices o, the +e*i/+ 6irate parae to the *irection o, propa-ation o, .a6e
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
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2
The trans6erse .a6es consist o, crests an* tro/-hs
The on-it/*ina .a6es consist o, co+pression an* rare ,riction
3
The *istance et.een t.o The *istance et.een t.o crests or t.o tro/-hs is co+pressions or t.o rare cae* .a6een-th ,rictions is cae* .a6een-th
=
#a6es pro*/ce* in .ater are the ea+pes o, trans6erse .a6es
So/n* .a6es are the ea+pe o, co+pressiona .a6es
&ipple tank:
& rippe tan; is a *e6ice .ith the hep o, .hich .e st/*y 6ario/s properties o, .ater .a6es 2onstruction:
& rippe tan; consists o, a rectan-/ar tray containin- .ater tte* .ith a transparent -ass at the otto+ & i-ht / is e* ao6e the tray .hie the i+a-e o, the .a6es can e seen on a 6ie.in- screen pace* at the otto+ o, the tray & +echanica +otor *ist/rs the .ater in *iDerent .ays an* th/s .a6es are pro*/ce* 4orking:
7ario/s ;in*s o, .a6es can e pro*/ce* y *ist/rin- .ater in *iDerent +anner #hen the i-ht shines thro/-h the .ater The crests in the .ater appear as ri-ht an* .hie the tro/-h appears as *ar; an* on the 6ie.in- screen The .a6e properties can e *e+onstrate* as /n*er
"roperties of 5a3es: $. &e8ection of 5a3es:
The o/ncin- ac; o, a .a6e ,ro+ a certain s/r,ace is cae* re,ection o, .a6es In rippe tan;5 reection o, .a6es can e *e+onstrate* y pacin- an /p9 ri-ht s/r,ace in .ater as sho.n in the -/re
*. &efraction of 5a3es:
The chan-e in path o, the .a6es5 .hen they enter ,ro+ one +e*i/+ to another +e*i/+ is cae* re,raction o, .a6es
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
11 NORTH HILLS SCHOOL COLL!"!
The re,raction o, .a6es can e *e+onstrate* in a rippe tan; y pacina pastic sheet in the otto+ portion o, the tray #e sha oser6e that .hen the .ater .a6es enter ,ro+ the shao. .ater into *eeper .ater they si-hty chan-e their path as sho.n in the -/re The spee* o, the .a6es is -reater in *eeper .ater than in shao. .ater
-. 0i7raction of 5a3es:
The en*in- o, .a6es aro/n* the e*-e o, an ostace OR Sprea*in- o, .a6es a,ter passin- thro/-h a s+a openin- is cae* *iDraction o, .a6es #hen the .a6es pass thro/-h an openin- .hose si?e is s+aer than the .a6een-th o, the .a6e then they sprea* o/t this sprea*in- is cae* *iDraction o, .a6es In rippe tan; *iDraction o, .a6es can e *e+onstrate* y pacint.o strai-ht ro*s .ith a s+a openin- et.een the+ #hen the .a6es pass thro/-h the openin- they *iDract aro/n* the corners o, the openin-
. %nterference of 5a3es:
#hen the t.o .a6es are passin- thro/-h the sa+e point si+/taneo/sy5 then the co+ine* eDect o, the t.o .a6es in the o6erappinre-ion is cae* inter,erence o, .a6es a Constr/cti6e inter,erence estr/cti6e inter,erence
2O(2E"T9'6 9E#T%O(# .$ the mass attached to a 3ibrating spring is increased four times. 4hat is the a7ect on the time period and freuency of oscillation of mass spring system; 'ns &s .e ;no. that the ti+e perio* an* ,re
y4 # = 2π
m !
f
=
1
!
2π
m
No. .hen the +ass is increase* ,o/r ti+es5 then .e repace >+’ y >=+’ in e
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
#
⇒ #
⇒ f / =
4m
⇒ # / = 2π ⇒
12 NORTH HILLS SCHOOL COLL!"!
!
/
!
2π
4m
1 1 ⇒ f / = 2 2π
m = 2 2π ! = 2 # − − − − − 1
/
1
⇒
f /
=
1 2
!
m
f − − − − − −2
!
eco+es i;e a si+pe pen*//+ No. .e ;no. that the ti+e perio* o, si+pe pen*//+ is -i6en y5 #
= 2π
%
− − − − − −1
S
⇒ #
2
⇒ # 2
= 2π
⇒ # 2 =
4π 2
⇒ # 2 % = ⇒
% # 2 4 π 2
⇒=
2
% 2 2 = 4π %
%
4π 2
=
% # 2 4 π 2
− − − − − − − −2
No. .e .i set the pen*//+ into 6iration an* note the ti+e ,or one 6iration π .hich -i6es its ti+e perio* >T’ /ttin- the 6a/es o, T5 - an* in e
. -. 4ill the period of a 3ibrating s5ing increases, decreases or remains constant by addition of more 5eight; 'ns. The 6iratin- s.in- can e consi*ere* as si+pe pen*//+5 .hose ti+e perio*
is -i6en y e
= 2π
%
− − − − − − − −1
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
13 NORTH HILLS SCHOOL COLL!"!
ro+ ao6e e6’ 5 its .a6een-th > ’ an* its ,re,’ are reate* y
the e
= f λ − − − − − −1
#e aso ;no. that the spee* o, .a6es in *eeper .ater is -reater than the spee* o, the .a6es in shao. .ater Then accor*in- to e.E of a simple pendulum 5hen the bob is at, +i? Mean position +ii? E!treme position 'ns: (i)9 The si+pe pen*//+ is sho.n in the -/re point @OA represent the +ain
position o, a si+pe pen*//+ .hie point @&AA&A represents the etre+e position o, the si+pe pen*//+ &t +ain position5 the 6eocity o, si+pe pen*//+ is +ai+/+ */e to restorin- ,orce */rin- osciation &s .e ;no. that5 F!182 +6 25 so */e to +ai+/+ 6eocity5 the F! .i e aso +ai+/+ at +ean position */rinosciation (ii)9 &t etre+e position5 the si+pe pen*//+ co+es to rest +o+entariy an* then +o6e ac; to.ar*s +ean position */e to restorin- ,orce Th/s the 6eocity o, si+pe pen*//+ is ?ero at etre+e position So the F! o, si+pe pen*//+ .i e ?ero at etre+e position .@: The diagram sho5n in the Agure, a 5a3e mo3ing into shallo5er 5ater. 4hy the 5a3e length of the 5a3e is reduced; 'ns: #e ;no. that the spee* o, .a6e in *eep .ater is -reater that the spee* o,
.a6e in shao. .ater #e ;no. that the reation 8. spee* o, .a6e en-th is -i6e y5 v
= f λ − − − − − −1
No. .hen a .a6e enters into shao. .ater ,ro+ *eep .ater5 its spee* .i e *ecrease &ccor*in- to e< (1)5 i, spee* o, a .a6e *ecreases5 than its .a6e λ
en-th @ A .i aso *ecrease .B: ' dipper mo3ing up and do5n makes 5a3e in ripple tank. 4hat 5ill happen 5hen the dipper freuency is increased; 'ns: &s .e ;no. that5
⇒
v
=
f λ
f
=
v
λ
− − − − −1
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
1= NORTH HILLS SCHOOL COLL!"!
I, 6 constant then e
=
⇒ f ∝
constant 1
λ
1
λ
− − − − − −2
Reation 2 sho.s that ,re
#ritten an* co+pose* y %ahoor &h+a* 'Sc hysics
Chapter No: 10 #RITT!N B$: %&HOOR &H'&
1 NORTH HILLS SCHOOL COLL!"!
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
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SOUND #ound:
The sensation ,et y o/r ear is cae* so/n* OR So/n* is a ,or+ o, ener-y that pro*/ces the sensation o, hearin- in ear E!planation:
So/n* is a ,or+ o, ener-y .hich tra6es thro/-h a +e*i/+ in the ,or+ o, on-it/*ina .a6es an* pro*/ce the sensation o, hearin- .hen ,as /pon the ear +e+rane "roduction of sound:
Three thin-s are necessary ,or pro*/ction an* hearin- o, so/n* 1 7iratin- o*y *e6ice
2 Trans+ittin- +e*i/+
3 Hearin-
$. )ibrating body:
The so/n* .a6es can e pro*/ce* y the 6iration o, a 6iratino*y in a +e*i/+ or ea+pe a t/nin- ,or; is a *e6ice /se* ,or the pro*/ction o, so/n* in aoratory #hen .e str/c; the t/nin- ,or; on a r/er pa* the pron-s e-in to 6irate an* a specia so/n* is pro*/ce* *. Transmitting medium:
#hen a o*y 6irates it trans,ers its ener-y to the s/rro/n*in+e*i/+ The trans+ittin- +e*i/+ trans+its this ener-y ,ro+ the so/rce to the recei6er y +eans o, so/n* .a6es The +e*i/+ co/* e soi*5 i
&ny *e6ice that can *etect so/n* .a6e can e cae* as hearin*e6ice !ar is a *e6ice that con6erts so/n* .a6es into the sensation o, hearin- The ener-y o, so/n* .a6es set the +e+rane o, ear or other *e6ice into 6irations The 6iration o, the so/rce an* 6irations o, +e+rane posses sa+e characteristics5 so the istener hears the so/n* #ound 5a3es do not tra3el through 3acuum:
So/n* .a6es nee* a +ateria +e*i/+ ,or their propa-ation It cannot tra6es thro/-h 6ac//+ It can e pro6e* .ith the hep o, the ,oo.in- eperi+ent !peri+ent: Consi*er an eectric e connecte* .ith an eectric circ/it pace* in a e Jar as sho.n in the -/re #hen the circ/it is cose* the ha++er hits the e an* th/s the so/n* pro*/ce* propa-ates thro/-h air an* nay reaches to o/r ear
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
1G NORTH HILLS SCHOOL COLL!"!
#hen air is p/+pe* o/t -ra*/ay ,ro+ the Jar .ith the hep o, 6ac//+ p/+p5 then the intensity o, so/n* *ecreases inay no so/n* can e hear* .hen air is totay p/+pe* o/t o, the Jar an* 6ac//+ is create* Th/s so/n* re
There are certain characteristics o, so/n* y .hich one so/n* can e *istin-/ishe* ,ro+ another so/n* These characteristics are -i6en eo. $. 6oudness of sound:
Lo/*ness o, so/n* enaes /s to *istin-/ish et.een a ,aint an* o/* so/n* Lo/*ness *epen*s /pon the ,oo.in- ,actors i
ii
iii
&rea o, the 6iratin- o*y: The ar-er the area o, 6iratin- o*y o/*er .i e the so/n* pro*/ce* an* 6ice 6ersa or ea+pe the *r/+ pro*/ces a o/* so/n* as co+pare* .ith that o, pro*/ce* y a *hooac Si+iary a schoo e pro*/ces o/* so/n* */e to ar-e area as co+pare* to that o, ho/se e &+pit/*e o, 6iratin- o*y: Lar-er the a+pit/*e o, 6iratino*y5 o/*er .i e the so/n* pro*/ce* .hie the so/n* .i e o. i, the a+pit/*e .i e s+a or ea+pe a *r/+ pro*/ces o/* so/n* .hen its +e+rane is str/c; stron-y .hereas so/n* .i e ,aint i, the +e+rane is str/c; -enty istance ,ro+ 6iratin- o*y: The o/*ness o, a so/n* increases or *ecreases as the *istance et.een the so/rce an* istener *ecreases or increases respecti6ey
*. %ntensity of sound:
The ener-y carrie* y so/n* .a6es per /nit ti+e per /nit area pace* perpen*ic/ar to the *irection o, propa-ation o, .a6es is cae* intensity o, so/n* Mathematically: I
=
& A × t
#here >I’ is the intensity o, so/n* .hen ener-y >!’ is trans,erre* thro/-h an area >&’ in ti+e inter6a >t’ The /nit o, intensity o, so/n* is .att per s
It is a reation et.een o/*ness o, so/n* an* its
intensity #tatement:
&ccor*in- to #eer echner’s a.5 @the o/*ness o, so/n* is *irecty proportiona to the o-arith+ o, intensityA
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
1 NORTH HILLS SCHOOL COLL!"!
∝ #o% I = ! #o% I − − − − − − − 1
'
⇒ '
!;’ is constant o, proportionaity an* its 6a/e *epen*s /pon the syste+ o, /nits
%ntensity le3el or sound le3el:
The *iDerence et.een the o/*ness o, t.o so/n*s .here one so/n* is ,aintest a/*ie so/n* is ;no.n as intensity e6e or so/n* e6e Let L o e the o/*ness o, ,aintest a/*ie so/n* an* L e the o/*ness o, any t.o e6es Then '0 '
= ! #o% I 0 − − − − − −1 = ! #o% I − − − − − − − 2
No. ,or n*in- the intensity e6e .e s/tract the e
= ⇒ Intensity level = '
−
'0
! #o% I − ! #o% I 0
⇒ Intensity level =
! ( #o% I − #o% I 0 ) ! #o%
I I 0
−−−−−−−3
/ttin- ; 1 in e
⇒ Intensity level =
#o%
I I 0
− − − −4
bels
e is the /nit o, intensity e6e or so/n* e6e In ter+s o, *ecies .e .i /se the ,oo.in- e
⇒ Intensity level =
10 #o%
I I 0
− − − −&
decibels
ro+ e
The characteristic o, so/n* y +eans o, .hich .e can *istin-/ish et.een shri so/n* an* -ra6e so/n* is cae* pitch o, so/n*
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
1K NORTH HILLS SCHOOL COLL!"!
itch o, so/n* *epen*s /pon the ,re
The property o, so/n* y .hich t.o so/n*s o, sa+e ,re
#a6e ,or+ o, *iDerent instr/+ents ha6in- sa+e o/*ness an* pitch Musical sound:
& so/n* .hich pro*/ces peasin- sensation in ear is cae* a +/sica so/n* '/sica so/n* is co+pose* o, re-/ar an* /ni,or+ 6irations There is no s/**en chan-e in its .a6e ,or+ as sho.n in the -/re The so/n* pro*/ce* y sitar5 piano5 6ioin5 t/nin- ,or; etc are the ea+pes o, +/sica so/n* (oise:
& so/n* .hich pro*/ces *ispeasin- sensation in ear is cae* a +/sica noise S/ch a so/n* is co+pose* o, irre-/ar an* *isor*ere* 6irations There is s/**en chan-e in its .a6e ,or+ as sho.n in the -/re The so/n* o, eposion5 horn o, 6ehices5 an* so/n* o, *on;ey are the ea+pe o, noise
(oise pollution:
The ecessi6e noises .hich *isr/pt the aance or acti6ity o, i6in- or non i6in- thin-s in the en6iron+ent5 is cae* noise po/tion E!planation:
There are +any so/rces .hich ca/ses noise po/tion or ea+pe the horn o, 6ehices5 the +achinery /se* in constr/ction5 the o. yin- cra,ts5 o/* spea;ers5 +eta .or; etc ca/se noise po/tion
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
20 NORTH HILLS SCHOOL COLL!"!
Noise is n/isance eca/se o, its har+,/ eDect on h/+an ein-s5 ani+as5 pants an* other inert thin-s in en6iron+ent So+e har+,/ eDects o, noise po/tion are -i6en eo. 1 2 3 = E G
Noise ca/ses te+porary or per+anent *ea,ness It re*/ces the .or;in- eciency an* inter,eres .ith co++/nication It increases the rate o, errors .hich ca/ses acci*ents It *ecreases the aiity o, /n*erstan*in-5 istenin-5 .ritin- an* rea*ino, h/+ans It ca/ses *an-ero/s *iseases i;e oo* press/re5 heart proe+s an* +enta iness It *a+a-es the ner6o/s syste+ o, ani+as It *ecreases the pro*/cti6ity o, ani+as an* aDects the nor+a -ro.th o, pants Lo/* noise can aso aDect the hi-h /i*in- an* ri*-es etc
#peed of sound:
The *istance co6ere* y so/n* .a6es in /nit ti+e is cae* spee* o, so/n* The spee* o, so/n* *epen*s /pon the +e*i/+ in .hich they tra6e4 it is -reater in *enser +e*i/+ than in rare +e*i/+ 0etermination of speed of sound in air:
The spee* o, so/n* can e *eter+ine* y /sin- resonance t/e +etho* .hich .or;s on the principe o, resonance pheno+enon 2onstruction:
The eperi+enta arran-e+ent consists o, a -ass t/e .hich is connecte* to a .ater reser6oir as sho.n in the -/re The -ass t/e contain air co/+n .hose en-th can e increase or *ecrease y +o6in- the reser6oir /p an* *o.n 4orking:
& 6iratin- t/nin- ,or; o, ;no.n ,re
en* o, the t/e &s the en-th
λ 4 4 = λ
⇒ ⇒ #e ;no. that5
et.een no*e an* anti no*e is -i6en y
λ
=
=
4 − − − − − −1
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
21 NORTH HILLS SCHOOL COLL!"! v
=
f λ − − − − − −2
/ttin- e
=
f × 4
⇒ v = 4 f − − − − − 3
f
&s the 6a/es o, @ Aan* @ A are ;no.n5 so spee* o, so/n* can e cac/ate* In air the spee* o, so/n* is 330 +8sec
&e8ection of sound:
The o/ncin- ac; o, so/n* .hen it stri;es a har* s/r,ace is cae* reection o, so/n* E!planation:
&s .e ;no. that .a6es ha6e the property to reect So/n* .a6es aso reect ,ro+ the har* s/r,aces i;e .as5 +eta sheets5 py.oo* etc the reection o, so/n* *oes not re
Echo:
The repetition o, so/n* y reection o, so/n* .a6es ,ro+ a s/r,ace is ;no.n as echo E!planation:
#hen a person sho/ts in a i- e+pty ha5 .e rst hear his ori-ina so/n* &,ter a itte .hie5 .e hear the reecte* so/n* o, sho/t cae* echo Th/s an echo is si+py the reecte* so/n* I, .e sho/t at a .a ,ro+ 3== +eters a.ay5 the so/n* ta;es 1 secon* to reach the .a The so/n* ta;es 1 secon* to ret/rn So .e hear echo a,ter 2 secon*s 'udible freuency range:
The h/+an ear can hear ony those so/n*s .hose ,re
The a/*ie ,re
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
22 NORTH HILLS SCHOOL COLL!"!
The so/n*s .hose ,re
The so/n*s o, ,re
The so/n*s o, ,re
#e cannot hear the so/n* .hose ,re
The st/*y o, pro*/ction5 propa-ation an* properties o, so/n* as .e as 6ario/s appications o, so/n* is ;no.n as aco/stics OR
The st/*y o, so/n* is cae* aco/stics
'coustic protection:
The ei+ination o, aco/stic ,actors .hich aDect the cear hearin- o, so/n* is ;no.n as aco/stic protection E!planation:
The ,actors .hich aDect the aco/stics o, roo+s an* has are as ,oo.s 1 !cho so/n* at certain spots $. Echo:
2 Re6ereration
3 oc/sin- o,
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
23 NORTH HILLS SCHOOL COLL!"!
The reection o, so/n* ,ro+ the har* s/r,ace is cae* echo Ori-ina so/n* cannot e hear* ceary */e to echo The echo can e a6oi*e* y +a;in- /se o, asorin- +aterias in the .as o, has an* roo+s *. &e3erberation:
The presence o, so/n* a,ter the so/n*in- so/rce has stoppe* is ;no.n as re6ereration It ca/ses -enera con,/sion o, so/n* i+pressions on ear It can e a6oi*e* y /sin- asorin- thin-s i;e carpet an* c/rtains in has an* roo+s -. ocusing of sound at certain spots:
The c/r6e* .as ,oc/s the so/n* .a6es at a certain spots Th/s so/n* cannot e hear* ceary at so+e paces It can e a6oi*e* y /sin- at .as instea* o, c/r6e* .as 4ritten and composed by: C'
2O(2E"T9'6 9E#T%O(# $. 4hy the 5a3es produced by simple pendulum cannot be heard;
The +e+rane o, h/+an ear can e 6irate* y those so/n*s .hose ,re
The ,re
o*y "reater is the s/r,ace area o, 6iratin- o*y5 o/*er .i e the so/n* pro*/ce* y that o*y an* 6ice 6ersa
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
2= NORTH HILLS SCHOOL COLL!"!
Since .e ;no. that the s/r,ace area o, a schoo e is ar-er So it pro*/ces o/*er so/n* .hen str/c; */e to its ar-er s/r,ace area -. 4hy the sound produced by a dhoolF is louder than a dhoolacF; 'ns. The o/*ness o, so/n* *epen*s /pon the area o, 6iratin- o*y ie
"reater the s/r,ace o, 6iratin- o*y5 -reater .i e the o/*ness o, so/n* pro*/ce* y that o*y an* 6ice 6ersa Since the s/r,ace area o, a >*hoo’ is -reater than the s/r,ace o, a >*hooac’ So the so/n* pro*/ce* y a >*hoo’ is o/*er than that o, a >*hooac’ . %n 5hich medium air or 5ater, an echo is heard sooner and 5hy; 'ns, the spee* o, so/n* *epen*s /pon the easticity o, the +e*i/+ ie
-reater is the easticity o, the +e*i/+5 -reater .i e the spee* o, so/n* an* 6ice 6ersa &s .ater is +ore eastic than air5 so the spee* o, so/n* in .ater .i e -reater than .ater Th/s an echo is hear* sooner in .ater as co+pare* to air 1. %f a ringing bicycle bell is held tightly by hand, it stops producing sound 5hy; 'ns: a rin-in- icyce e pro*/ces so/n* */e to 6irations No. i, .e he*
the rin- e ti-hty y han*5 then its 6iration s .i stop as a res/t pro*/cin- no so/n* =. 4hy sound cannot tra3el through 3acuum;
The so/n* .a6es are on-it/*ina .a6es (+echanica .a6es) Th/s nee*s a +ateria +e*i/+ ,or their propa-ation &s in 6ac//+5 there is no +ateria +e*i/+5 so so/n* .a6es cannot tra6es thro/-h 6ac//+ 'ns.
G. 4hy sound cannot be heard on moon; 'ns. The so/n* .a6es are on-it/*ina .a6es (+echanica .a6es) Th/s
nee*s a +ateria +e*i/+ ,or their propa-ation &s there is no +ateria +e*i/+ in the at+osphere o, +oon thro/-h .hich so/n* .a6es can pass Th/s a so/n* cannot e hear* on the +oon @. 4hen the 5ire of sitar is plucked. 4hat of 5a3es are produced in the air; 'ns #hen the .ire o, sitar is p/c;e*5 then so/n* .a6es are pro*/ce* in air
These so/n* .a6es propa-ate thro/-h air in the ,or+ o, on-it/*ina .a6es .hich consists o, co+pressions an* rare,actions .hich are pro*/ce* one a,ter the other in a certain or*er
B.
ahea* #hen an oJect appears in their path5 the /trasonic reects ,ro+ that oJect an* is recei6e* y the at in the ,or+ o, echo In this .ay5 the at
Chapter No: 11 #RITT!N B$: %&HOOR &H'&
2 NORTH HILLS SCHOOL COLL!"!
co+es to ;no. ao/t the oJect in their path an* th/s chan-e their path Th/s the ats re+ain sa,e ,ro+ coi*in- .ith oJects at ni-ht
4ritten and composed by: C'
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
2E NORTH HILLS SCHOOL COLL!"!
"eo+etrica Optics
CH&T!R NO:12
Q1. What is meant by refectin ! "i#ht$ State an% e&'"ain "a(s ! refectin (ith %ia#ram$
&ns Refectin ! "i#ht)* .hen rays o, i-ht tra6ein- in one +e*i/+ stri;es the o/n*ary o, another +e*i/+ a part o, it is sent ac; in the sa+e +e*i/+5 it is ;no.n as reection o, i-ht OR The o/ncin- ac; o, rays o, i-ht ,ro+ a +e*i/+ is cae* reection o, i-ht Li-ht +osty reects ,ro+ s+ooth an* poishe* s/r,aces i;e +irrors an* +etas Refectin ! "i#ht !rm '"ane mirrr)*
The pheno+ena reection o, i-ht is epaine* ,ro+ the reection o, i-ht ,ro+ pane +irror in the ao6e -i6en *ia-ra+ & pane +irror '' is sho.n in the ao6e ,i-/re Inci*ent rays o, i-ht &O stri;es the +irror at the point o, inci*ence @OA an* then reects as ray OB ,ro+ the point o, inci*ence @OA ON is ;no.n as the nor+a to the +irror '' The an-e et.een the inci*ent ray an* the nor+a is cae* an an-e o, inci*ent .here as the an-e et.een the nor+a an* the reecte* ray is ;no.n as an-e o, reection La(s ! refectin ! "i#ht)* The reection o, i-ht ,ro+ a pane s/r,ace oeys t.o a.s5 .hich are ;no.n as the a. o, reection o, i-ht These t.o a.s are -i6en eo.
1 irst the a. o, reection states that the inci*ent ray &O5 reecte* ray OB an* the nor+a ON a ie on the point o, inci*ence @OA in the sa+e pane 2 Secon* a. o, reection states that the an-e o, inci*ence to the an-e o, reection +
∠i
∠r
∠i
is a.ays e
ie
+
∠r
Q+. What are s'herica" mirrr$ E&'"ain its ty'es (ith the he"' ! % ia#ram$
&ns S'herica" ,irrrs) * it is part o, a spherica she .ith its inner or o/ter s/r,ace poishe* to reect i-ht cae* spherica +irrors Spherica +irrors are o, t.o types’ ie conca6e +irror an* con6e +irror 1 Cnca-e ,irrr)* & spherica +irror .hose inner s/r,ace poishe* to reect i-ht is cae* conca6e +irror
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
2G NORTH HILLS SCHOOL COLL!"!
Conca6e +irror has the aiity to con6er-e a parae ea+ o, i-ht4 there,ore it is cae* a con6er-in- +irror The inner shinnin- s/r,ace o, spoon is an ea+pe o, conca6e +irror Natre ! ima#e !rme% by Cnca-e mirrr) * Rea an* in6erte* i+a-es are ,or+e* y conca6e +irror The si?e an* *istance o, the i+a-e ,or+e* y conca6e +irror *epen*s on the *istance o, the oJect ,ro+ conca6e +irror
2 Cn-e& ,irrr)* & spherica +irror .hose o/ter s/r,ace is poishe* to reect i-ht is cae* con6e +irror
Con6e +irror has the aiity to *i6er-e a parae ea+ o, i-ht4 there,ore it is aso cae* a *i6er-in- +irror The o/ter /-in- shinnin- s/r,ace o, a spoon is an ea+pe o, con6e +irror Natre ! ima#e !rme% by cn-e& mirrr) * 6irt/a5 erect an* *i+inishe* i+a-e is aso ,or+e* y con6e +irror ,or any *istance o, an oJect ,ro+ con6e +irror Q/. Write sme ses ! s'herica" mirrr$
&ns So+e i+portant /ses o, spherica +irrors are -i6en eo. 0ses ! Cnca-e ,irrr)*
i)
ii)
iii)
i6) 6)
&s sha6in- +irror: 9 conca6e +irror o, ar-e ra*i/s o, c/r6at/re is /se* as sha6in- +irror #hen ,ace is cose to the +irror an enar-e*5 erect an* 6irt/a i+a-e is ,or+e* .hich hep in +a;in- a cean an* neat sha6e Pse* y *octors an* *entists: 9 octor Pse conca6e +irror to ea+ine ear5 nose an* throat entists aso /se a s+a conca6e +irror to ha6e a oo; o, ac; si*e o, tooth an* ca6ity in it &s oJecti6e o, reectin- teescope: 9 in one ;in* o, teescope5 a conca6e +irror is /se* as oJecti6e /e to ar-er apert/re -reat a+o/nt o, i-ht ,ro+ the oJect is inci*ent on this conca6e +irror So a cear i+a-e o, the oJect is seen y s/ch teescope In +icroscope:9 conca6e +irror are aso /se* to concentrate i-ht on +icroscope si*e In a/to+oies hea*i-ht an* search i-hts: 9 Conca6e +irrors are /se* ehin* the / in hea*i-hts an* search i-hts in a partic/ar *irection
0ses ! Cn-e& ,irrr)*
Chapter No: 12 #RITT!N B$: %&HOOR &H'& i) ii) iii)
2 NORTH HILLS SCHOOL COLL!"!
The 7ehices si*e +irror: 9 con6e +irror are /se* as si*e +irror in 6ehices to oser6e rear 6ie. &t roa* en*: 9 Lar-e con6e +irrors are o,ten pace* at *an-ero/s roa* en*s ,or sa,e *ri6e &t Shoppin- 'as: 9 Lar-e con6e +irror are /se* at shoppin- +as ,or sec/rity to oser6e e6ery pace o, a shoppin- +a
Q. What is meant by re!ractin ! "i#ht$ State an% e&'"ain "a(s ! re!ractin (ith the he"' ! a %ia#ram$
&ns Re!ractin ! "i#ht)* The chan-e in 6eocity an* *irection o, i-ht .hen it passes oi
La(s ! re!ractin)* Re,raction o, i-ht oeys the ,oo.in- t.o a.s
i) ii)
The nor+a inci*ent ray5 re,racte* ray an* the nor+a at the point o, inci*ence5 a ie at the sa+e pane The ratio o, sine o, an-e o, inci*ence an* the sine o, an-e o, re,raction is constant ,or a -i6en pair o, +e*ia
,athematica""y)*
Secon* a. o, re,raction is aso ;no.n as Sne’s a. '
=
sin ∠i sin ∠!
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
2K NORTH HILLS SCHOOL COLL!"!
Q2. De3ne re!racti-e in%e&. H( it is re"ate% t -e"city ! "i#ht in a 'air ! me%ia$
&ns Re!racti-e In%e&) * The re,racti6e in*e is the ratio o, the 6eocities o, i-ht in the air or 6ac//+ to the 6eocity o, i-ht in a -i6en +e*i/+ Th/s the re,racti6e in*e o, -ass .ith re,erence to air is -i6en y: ' =
#ocit of #i%ht in ai! #ocit of #i%ht in %#ass
The re,racti6e in*e o, a s/stance *oes not *epen* on the an-e o, inci*ence /t *epen*s on the nat/re o, +ateria o, the +e*i/+ an* on the .a6een-th o, the i-ht /se* Q4. De3ne the terms centre ! cr-atre5 ra%is ! cr-atre5 '"e5 'rinci'a" a&is5 a'ertre5 'rinci'a" !cs an% !ca" "en#th$
&ns Centre ! cr-atre : 9 The centre o, the hoo. sphere o, .hich +irror is a part is cae* its centre o, c/r6at/re It is represente* y C centre o, c/r6at/re o, a conca6e +irror is in ,ront o, it /t that o, con6e +irror is ehin* it
Ra%is ! cr-atre: 9 The ra*i/s o, the hoo. sphere o, .hich +irror is a part is cae* ra*i/s o, c/r6at/re o, that +irror It is *enote* y R 6"e: 9 the centre point o, a +irror is cae* its poe It is *enote* y 6rinci'a" a&is: 9 The strai-ht ine passin- thro/-h the poe @A an* the centre o, c/r6at/re @CA o, a +irror is cae* the principa ais o, that +irror A'ertre: 9 The area o, +irror epose* to the inci*ent i-ht is cae* apert/re 6rinci'a" !cs: 9 The point at .hich the reecte* rays ,ro+ conca6e +irror con6er-e is cae* principa ,oc/s o, conca6e +irror It is *enote* y principa ,oc/s o, conca6e +irror is in ,ront o, a conca6e +irror
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
30 NORTH HILLS SCHOOL COLL!"!
The point ,ro+ .hich the i-ht rays appear to *i6er-e a,ter reection ,ro+ conca6e +irror is cae* principa ,oc/s o, con6e +irror It is *enote* y principa ,oc/s o, con6e +irror is ehin* the con6e +irror
7ca" "en#th: 9 The *istance et.een the poe @A an* principa ,oc/s @A o, the +irror is cae* ,oca en-th It is *enote* y @,A
oca en-th o, conca6e +irror is consi*ere* positi6e .hie ,oca en-th o, con6e +irror is consi*ere* ne-ati6e
Q8. E&'"ain the rays ! "i#ht that are se% t "cate the ima#e !rme% by cnca-e mirrr$
&ns The ,oo.in- rays o, i-ht are /s/ay /se* to ocate the i+a-e ,or+e* y conca6e +irror 1 The rays o, i-ht tra6ein- parae to principa ais passes thro/-h principa ,oc/s @A a,ter reection ,ro+ conca6e +irror
2 The rays o, i-ht passin- thro/-h principa ,oc/s @A eco+e parae to principa ais a,ter reection ,ro+ conca6e +irror
3 The rays o, i-ht passin- thro/-h the centre o, c/r6at/re @CA o, conca6e +irror is reecte* ac; aon- the sa+e path
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
31 NORTH HILLS SCHOOL COLL!"!
= The rays o, i-ht inci*ent at the poe o, a conca6e +irror reect .ith the sa+e an-e as the inci*ent ray +a;es .ith the principa ais
Q9. Discss the natre ! the ima#e !rme% by cnca-e mirrr as the b:ect is br#ht c"se t cnca-e mirrr$
&ns The type o, i+a-e ,or+e* y a conca6e +irror *epen*s on the position o, an oJect in ,ront o, a conca6e +irror I, the *istance o, an oJect ,ro+ a conca6e +irror is chan-e* than5 nat/re5 si?e an* ocation o, i+a-e is aso chan-e* The ,oo.in- res/ts are otaine* y chan-in- the *istance o, an oJect ,ro+ conca6e +irror 1 4hen the obHect is beyond the centre of cur3ature: 9 i, the oJect is pace* eyon* the centre o, c/r6at/re @CA o, the conca6e +irror than its rea5 in6erte* an* s+aer i+a-e is ,or+e* et.een centre o, c/r6at/re @CA an* ,oc/s @A
2 4hen the obHect is placed at centre of cur3ature: ? i, the oJect is pace* at the centre o, c/r6at/re @CA o, a conca6e +irror then its rea an* in6erte* i+a-e o, the sa+e si?e as that o, the oJect is ,or+e* at the centre o, c/r6at/re
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
32 NORTH HILLS SCHOOL COLL!"!
3 4hen the obHect is placed bet5een principal focus “” and the centre of cur3ature “2”:? i, the oJect is pace* et.een @CA an* @A then it’s rea5 in6erte* an* +a-nie* i+a-e .i e ,or+e* eyon* @CA
= 4hen the obHect is placed at the principal focus “”:? i, oJect ies at ,oc/s @A o, a conca6e +irror than hi-hy +a-nie*5 in 6erte* an* rea i+a-e .i e ,or+e* at innity
4hen obHect is placed bet5een pole “"” and focus “”:? i, the oJect is pace* et.een the poe @A an* ,oc/s @A o, a conca6e +irror5 than 6irt/a5 erect an* enar-e* i+a-e appears ehin* the +irror
Q;. Deri-e the s'herica" mirrr e<atin !r a cnca-e mirrr$
&ns S'herica" ,irrr E<atin :9 & ,or+/a .hich -i6es the reation et.een i+a-e *istance oJect *istance an* ,oca en-th o, a +irror is ;no.n as the +irror ,or+/a or +irror e
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
33 NORTH HILLS SCHOOL COLL!"!
In or*er to *eri6e the +irror ,or+/a5 #e .i e a ray *ia-ra+ Consi*er t.o si+iar trian-es &B an* &B as t.o trian-es are si+iar there,ore A(
P(
=
A′ ( ′
− − − − −1
P ( ′
Trian-e &B an* ! are aso si+iar there,ore A( &P
=
("
=
("
"P
!&B there,ore A(
′ ′ A (
"P
− − − − − −2
Co+parin- e
=
P ( ′
(" "P
&s B B95 there,ore P( P ( ′
=
P( − "P "P
In the -i6en ,i-/re B5 < B an* , there,ore5 ) *
=
) − f f
By cross +/tipication
= * ( ) − f ) ) f = * ) − * f ) f
i6i*in- oth si*es y #q( ) f ) * f ) f ) * f 1
* 1
f
= =
* ) − * f
= = 1
f 1
)
) * f * ) ) * f
− +
−
* f ) * f
1
) 1
*
This is ;no.n as +irror ,or+/a It -i6es reation et.een the oJect *istance5 i+a-e *istance an* ,oca en-th o, a spherica +irror
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
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Q1=. De3ne "inear ma#ni3catin. Write the si#n cn-entin !r s'herica" mirrr$
&ns Linear ,a#ni3catin : 9 The ratio o, the si?e o, the i+a-e to the si?e o, the oJect is cae* inear +a-nication The ratio o, the i+a-e *istance to the oJect *istance is aso cae* inear +a-nication ,athematica""y :9 M = M =
Si, of ima% Si, of o*+ct
hi ho
=
=
Ima% $istanc O*+ct $istanc
* )
Si#n Cn-entin : 9 The ,oo.in- si-n con6ention is a*opte* to otain the correct res/t in a -i6en proe+ o, i+a-e ,or+e* y a spherica +irror
(i) (ii) (iii)
istance o, rea oJect an* rea i+a-es are ta;en positi6e istance o, 6irt/a oJects an* 6irt/a i+a-es are ta;en as ne-ati6e The ,oca en-th o, a conca6e +irror is ta;en positi6e an* that o, con6e +irror is ta;en as ne-ati6e
Q11. E&'"ain tta" interna" refectin ! "i#ht an% critica" an#"e. A"s (rite a''"icatins ! tta" interna" refectin ! "i#ht$
&ns Critica" an#"e : 9 The an-e o, inci*ence in the *enser +e*i/+ ,or .hich the an-e o, re,raction in rare +e*i/+ eco+es K0 is cae* critica an-e Tta" interna" refectin ! Li#ht :9 .hen the an-e o, inci*ence in the *enser +e*i/+ eco+es -reater than the critica an-e Uc5 there is no re,racte* ea+ & the rays are internay reecte* ac; in the opticay *enser +e*i/+ S/ch a reection is cae* interna reection o, i-ht
Cn%itins !r tta" interna" refectin :9 the ,oo.in- con*itions +/st e satise* ,or the eDect o, tota interna reection
Chapter No: 12 #RITT!N B$: %&HOOR &H'& i) ii)
3 NORTH HILLS SCHOOL COLL!"!
The inci*ent i-ht +/st pass ,ro+ a *enser +e*i/+ into a rare +e*i/+ The an-e o, inci*ence in *enser +e*i/+ +/st e -reater than the critica an-e o, the +e*i/+
A''"icatin ! tta" interna" refectin :9
i)
ii) iii)
i6)
The 6erisc'e: 9 it is an optica instr/+ent /se* to see the oJects ao6e the e6e o, 6ie.er or .hen the oJects cannot e seen *irecty The prison periscopes are /se* in tan;s an* s/+arines The binc"ars : 9 The inoc/ars aso +a;e /se o, pris+ to re*/ce the en-th o, the instr/+ent an* pro*/ce an erect i+a-e O'tica" 7ibers: 9 an i+portant appication o, tota interna reection is in the operation o, optica ers Optica ers are +a*e o, a core o, hi-h re,racti6e in*e i9e -ass or pastic The thic;ness o, the ers is ao/t the thic;ness o, the h/+an hair Optica res are no. .i*ey /se* in teeco++/nication in*/stries They can carry +/ch +ore in,or+ation than copper .ires They are aso i-hter an* are cheaper as co+pare* .ith copper caes En%sc'e:9 & 6ery i+portant appication o, tota interna reection is ,o/n* in en*oscope &n en*oscope is an optica instr/+ent .hich is /se* ,or 6ie.in- an* photo-raphin- the insi*e o, a hoo. ar-er o, the o*y s/ch as the a**er .o+ etc "astroscope is an en*oscope to 6ie. the sto+ach
Q1+. E&'"ain re!ractin ! a "i#ht thr#h a 'rism$
&ns Re!ractin ! "i#ht thr#h a 'rism : 9 & pris+ is a transparent re,ractino*y ha6in- three rectan-/ar an* t.o trian-/ar s/r,aces An#"e ! a 'rism:9 the an-e et.een the t.o re,ractin- rectan-/ar s/r,aces opposite to the ase is cae* the an-e o, pris+ U&
Re,raction o, i-ht thro/-h a pris+ is epaine* ,ro+ the -i6en *ia-ra+
! is the inci*ent ray to the ,ace &B o, a pris+ The inci*ent ray ! on enterin- the -ass pris+ is re,racte* to.ar*s the ase BC o, the pris+ #hen this re,racte* ray " e+er-es o/t o, the pris+5 it en*s a.ay ,ro+ the nor+a The e+er-ent ray "H has een *e6iate* ,ro+ its ori-ina paths !I I, .e pro*/ce "H ac;.ar* it .i +eet !I at O +a;in- an an-e IOH
∠
An#"e ! %e-iatin > IOH?:9 The an-e thro/-h .hich the e+er-ent ray has een *e6iate* is cae* the an-e o, *e6iation (UIOH) An#"e ! minimm %e-iatin Dm >@IOH ):9 #hen the re,racte* ray eco+es parae .ith ase BC o, the pris+ then the an-e o, *e6iation eco+es +ini+/+
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
3E NORTH HILLS SCHOOL COLL!"!
an* is cae* the an-e o, +ini+/+ *e6iation ' the 6a/e o, an-e o, *e6iation *epen*s /pon the ,oo.in- ,actors i) ii) iii)
&n-e & o, the pris+ The re,racti6e in*e o, the +ateria o, the pris+ The an-e o, inci*ence
The in*e o, re,raction o, the +ateria o, the pris+ can e *eter+ine* y the reation
f!acti" in$. - η
=
sin( A + sin
+m 2
)
A 2
Q1/. De3ne "ens5 its (rin# an% ses. A"s (rite the ty'es an% sbty'es ! "enses$
&ns. Lens:9 & ens is a piece o, transparent re,ractin- +ateria s/ch as -ass or pastic .hich re,racts i-ht in a re-/ar .ay Lens is o/n*e* y one or t.o spherica s/r,aces Wrin#: 9 The .or;in- o, the ens is ase* on the re,raction o, i-ht rays .hen they are passin- thro/-h it 0ses ! "ens: 9 enses are .i*ey /se* in spectaces5 ca+eras5 proJectors5 optica instr/+ents H/+an eyes ha6e t.o specia crystaine enses .hich enaes it to ,or+ i+a-es Ty'es ! "enses: 9 There are t.o types o, enses Con6e ens an* conca6e ens
1) Cn-e& Lens:9 & ens that is thic;er at the centre than at the e*-es is cae* con6e ens Con6e ens con6er-es parae ea+ o, i-ht at a sin-e point an* hence is aso cae* con6er-in- ens Rea an* in6erte* i+a-es are ,or+e* ,ro+ con6e ens
Sb ty'es ! cn-e& "ens : 9 con6e ens has three s/ types
(i)
0ouble con3e! lens:? & ens ha6in- oth the s/r,aces con6e or c/r6e*
o/t.ar* is cae* icon6e ens or *o/e con6e ens
(ii)
"lano con3e! lens: 9 & ens ha6in- one s/r,ace ano an* other con6e
is cae* ano con6e ens
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
(iii)
3G NORTH HILLS SCHOOL COLL!"!
2onca3e 2on3e!: 9 & ens ha6in- one s/r,ace conca6e an* the other is
con6e is cae* conca6e con6e ens
2) Cnca-e Lens: 9 & ens that is thinner at the centre than at the e*-es is cae* conca6e ens Conca6e ens *i6er-es a parae ea+ o, i-ht an* is aso cae* *i6er-in- ens 7irt/a5 erect an* *i+inishe* i+a-es are ,or+s ,ro+ conca6e ens
Sb ty'es ! cnca-e "ens : 9 Conca6e ens has three s/ types
(i)
o/e Conca6e Lens: 9 & ens ha6in- oth the s/r,aces conca6e or c/r6e* in.ar* is cae* iconca6e ens or *o/e conca6e ens
(ii)
ano conca6e ens: 9 & ens ha6in- one s/r,ace pane an* the other is conca6e is cae* ano conca6e
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
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3 NORTH HILLS SCHOOL COLL!"!
Con6e Conca6e ens: 9 & ens ha6in- one s/r,ace con6e an* other conca6e is cae* Con6e Conca6e ens
Q1. De3ne the s'ecia" terms re"ate% t "ens$
&ns O'tica" Centre : 9 The centre point o, a ens is cae* optica centre Ps/ay it is *enote* y O optica centre @OA o, a ens ies on the principa ais & ray o, i-ht passin- thro/-h optica centre @OA s/Der no *e6iation an* - oes on strai-ht 6rinci'a" A&is: 9 & ine passin- thro/-h the optica centre o, the ens an* perpen*ic/ar to the oth ,aces o, the ens is cae* principa ais 6rinci'a" 7cs: 9 The point .here the re,racte* rays ,ro+ con6e ens con6er-e or appear to *i6er-e in case o, conca6e ens is cae* principa ,oc/s o, a ens
It is *enote* y & ens has t.o ,oci that are at e
&ns oo.in- are the +ost i+portant rays that enae /s to n* the position o, the i+a-e 1) Ray 1:9 &n inci*ent ray thro/-h optica centre @OA passes .itho/t en*in-
2) Ray +:9 &n inci*ent ray tra6es parae to the principa ais a,ter re,raction passes thro/-h principa ,oc/s @A o, the ens or appears to *i6er-e ,ro+ principa ,oc/s @A
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
3K NORTH HILLS SCHOOL COLL!"!
3) Ray /:9 &n inci*ent ray passin- thro/-h principa ,oc/s @A is re,racte* parae to the principa ais
Q14. Discss the natre an% the siBe ! the ima#e !rme% by cn-e& "ens (hen b:ect is br#ht c"ser t "ens$
&ns The type o, i+a-e ,or+e* y a con6e ens *epen*s on the *istance o, the oJect ,ro+ the ens #hen the oJect is ro/-ht coser to the con6e ens5 i+a-e o, *iDerent nat/re is ,or+e* The ,oo.in- cases i/strate the -raphica ray *ia-ra+ +etho* o, constr/ctin- the i+a-es o, an oJect (i)
When the b:ect is beyn% +7 :9 .hen an oJect &B is pace* eyon* 2 in a ,ront o, a con6e ens Its i+a-e &VBV .i e ,or+e* et.een an* 2 The i+a-e .i e *i+inishe*5 rea an* in6erte*
(ii)
When the b:ect is at +7 :9 .hen an oJect is pace* at 2 in ,ront o, a con6e ens The i+a-e .i e ,or+e* at 2 The i+a-e .i e o, sa+e si?e as that o, oJect5 rea an* in6erte*
(iii)
When an b:ect is bet(een 7 an% +7 :9 #hen an oJect is pace* in ,ront o, a con6e ens et.een an* 2 Then the i+a-e .i e ,or+e* at a *istance eyon* 2 ,ro+ the ens The i+a-e .i e +a-nie*5 rea an* in6erte*
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
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(i6)
When the b:ect is '"ace% at the !cs ! a cn-e& "ens : 9 #hen the oJect is at in ,ront o, the con6e ens Its i+a-e .i e at innity5 +/ch enar-e*5 rea an* in6erte*
(6)
When the b:ect is '"ace% bet(een 'tica" centre an% !cs : 9 #hen the oJect is pace* et.een optica centre an* principa ,oc/s Then the i+a-e .i e ,o/n* on the sa+e si*e ehin* the oJect The i+a-e .i e +a-nie*5 erect an* 6irt/a
Q18. Deri-e "ens !rm"a$
&ns Lens 7rm"a: 9 & ens ,or+/a -i6es the reationship et.een i+a-e *istance @
′ ′ A ( A( ′ ′ A (
= =
,( , ( ′ ) *
− − − − −1
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
=1 NORTH HILLS SCHOOL COLL!"!
Trian-e !C an* &’B’ are aso si+iar there,ore &,
′ ′ A (
,"
=
" ( ′
!C &B there,ore A( A′ ( ′ A( A′ ( ′
,"
=
" ( ′ ,"
=
∴ " ( ′ =
, ( ′ − ," ," = f , ( ′
=*
, ( ′ − ,"
and ," = f
Since ,ro+ the -/re -et A(
f
=
′ ′ A (
p/ttin- in ao6e e
* − f
− − − − − −2
Co+parin- e
f
=
* − f
By cross +/tipication * f = ) (* − f ) * f
= ) * − ) f
i6i*in- oth si*es y #q( * f ) * f * f ) * f 1 ) 1 f
= =
) * − ) f
=
) * f ) *
= f
)
) f
) * f ) * f
1 1
−
−
+
1 * 1 *
This e
Q19. De3ne '(er ! a "ens an% its nit$
&ns 6(er ! "ens:9 The po.er o, the ens is the +eas/re o, *e-ree o, con6er-ence or *i6er-ence o, ri-ht rays ,ain- on it
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
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The po.er o, ens *epen*s /pon its ,oca en-th The s+aer the ,oca en-th the -reater is the con6er-ence or *i6er-ence po.er o, the ens ,athematica""y :9 o.er o, ens is *ene* as the reciproca o, its ,oca en-th in +eters It is *enote* y +
=
+
=
1 oca# #n%th of a #ns in mt!s 1 f (m)
0nit ! '(er ! a "ens >? :9 The /nit o, po.er o, a ens *ioptre .hich is *ene* as @One *ioptre is the po.er o, a ens .hose ,oca en-th is one +eterA
Q1;. Write a nte n sim'"e micrsc'e$
&ns Sim'"e ,icrsc'e: 9 & si+pe +icroscope is a con6e ens o, short ,oca It is aso cae* +a-ni,yin- -ass Wrin#: 9 & si+pe +icroscope .or;s on the principa that .hen an oJect is pace* .ithin its ,oca en-th5 a +a-nie*5 6irt/a an* erect i+a-e is ,or+e* Since the i+a-e ,or+e* is ar-er than the oJect it eca/se easier to see the *etais o, the s+a oJect 0ses: 9 & si+pe +icroscope is /se* y .atch +a;ers to see the s+a parts o, a .atch ceary It is aso /se* y Je.eers to see the ne parts o, Je.eery etc
E&'"anatin: 9 In the -i6en ray *ia-ra+ a s+a oJect &B to the +a-nie* is pace* et.een the optica centres @CA an* ,oc/s @A o, the con6e ens So the erect5 6irt/a an* +a-nie* i+a-e &’B’ is ,or+e*
#hen .e oo; into the ens ;eepin- the eyes cose to the ens5 .e see the +a-nie* i+a-e &’B’ in .hich a the parts o, the oJect appear to e +/ch ar-er than they act/ay are #e a*J/st the position o, the ens in s/ch a .ay that the i+a-e is ,or+e* at a *istance o, ao/t 2c+ ,ro+ the eye #hich is the east *istance o, the *istinct 6isionM This is *one eca/se .hen the i+a-e is at east *istance o, *istinct 6ision5 then the eye can see it con6enienty .itho/t /n*/e strain ,a#ni3catin 'r%ce% by a sim'"e micrsc'e : 9 'a-nication o, a si+pe +icroscope is -i6en y M = 1 +
+ f
#here @A is the east *istance o, *istinct 6ision5 .hich is 2c+ @,A is the ,oca en-th o, a con6e In the -i6en +a-nication ,or+/a5 the 6a/e o, is constant i9e 2c+ it is cear ,ro+ the +a-nication ,or+/a that the s+aer the ,oca en-th o, a con6e ens5 -reater .i e its +a-nication
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
=3 NORTH HILLS SCHOOL COLL!"!
Q+=. Write %e!ects ! -isin. Its cases an% crrectness$
&ns The *e,ects o, 6ision arise */e to the inaiity o, the eye ens to pro*/ce sharp i+a-es at retina The t.o +ain *e,ects o, 6ision are:9 a) Short si-hte*ness ('yopia) ) Lon- si-hte*ness (Hyper+etropia) a) Shrt si#hte%ness:9 Short si-hte*ness is that *e,ect o, an eye */e to .hich an eye cannot see the *istant oJect ceary thro/-h it can see the neary oJects ceary Cases ! shrt si#hte%ness :9 This *e,ect o, eye is ca/se* */e to the hi-h con6er-in- po.er o, the eye ens or */e to the eye a ein- too on- So */e to the -reater con6er-in- po.er o, the eye ens in +yopic eye5 the i+a-e o, *istant oJect is ,or+e* in ,ront o, the retina an* hence the eye cannot see it ceary Crrectin ! shrt si#hte%ness :9 Short si-hte*ness is correcte* y /sinspectaces containin- conca6e enses5 .hen a conca6e ens o, s/itae po.er is pace* in ,ront o, the eye5 then the parae rays co+in- ,ro+ *istant oJect are rst *i6er-e* y conca6e ens an* then con6er-e* on retina y the action o, conca6e ens Th/s the i+a-e o, *istinct oJect is ,or+e* on the retina o, the eye an* hence the eye can see it ceary
) Ln# si#hte%ness:9 Lon- si-hte*ness is that *e,ect o, the eye */e to .hich the eye cannot see the neary oJects ceary /t it can see the *istant oJects ceary Cases ! "n# si#hte%ness:9 Lon- si-hte*ness is ca/se* */e to o. con6er-in- po.er o, the eye ens or */e to the eye a ein- too short /e to the a. con6er-in- po.er o, eye ens5 the i+a-e o, neary oJects is ,or+e* ehin* the retina an* hence the eye cannot see it ceary Crrectin ! "n# si#hte%ness :9 on- si-hte*ness is correcte* y /sinspectaces containin- con6e ens #hen a con6e ens o, s/itae con6er-in- po.er is pace* in ,ront o, the eye5 then the rays co+in- ,ro+ the neary oJect are rst con6er-e* y the con6e ens an* then y the eye ens /e to co+ine* con6er-in- action5 the i+a-e @IA o, the neary oJect is ,or+e* on the retina an* hence the eye can see the *istinct oJect ceary
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
== NORTH HILLS SCHOOL COLL!"!
SHORT Q0ESTIONS Q1. Dra( a "abe" %ia#ram t sh( the a? '"e b? centre ! cr-atre c? 'rinci'a" a&is %? 'rinci'a" !cs e? ra%is ! cr-atre$
&ns
Q+. De3ne !ca" "en#th an% ra%is ! cr-atre. What is the re"atin bet(een the !ca" "en#th an% the ra%is ! cr-atre in case ! a cnca-e mirrr$
&ns. 7ca" "en#th : 9 The *istance et.een the poe an* the principa ,oc/s o, a conca6e +irror is ;no.n as ,oca en-th oca en-th is *enote* y , Ra%is ! Cr-atre :9 The ra*i/s o, a hoo. sphere o, .hich a +irror is a part is cae* ra*i/s o, c/r6at/re o, conca6e +irror Ra*i/s o, c/r6at/re is *enote* y R Re"atin bet(een !ca" "en#th an% ra%is ! cr-atre :9 It has een ,o/n* that the ,oca en-th o, a conca6e +irror is e
i9e , R82
Q/. Name the s'herica" mirrr (hich has a? irta" 'rinci'a" !cs. b? Rea" 'rinci'a" !cs$
&ns a) Con6e +irror has 6irt/a principa ,oc/s eca/se in con6e +irror the reecte* rays appear to *i6er-e ,ro+ a ,oc/s ehin* the +irror Con6e
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
= NORTH HILLS SCHOOL COLL!"!
+irror ,or+ 6irt/a i+a-e .hich is not otaine* on the screen in ,ront o, tr/e +irror ) Conca6e +irror has rea principa ,oc/s eca/se in con6e +irror the reecte* rays con6er-e in ,ront o, the +irror on the screen Th/s conca6e +irror has rea principa ,oc/s an* ,or+ rea i+a-e .hich is otaine* on the screen in ,ront o, conca6e +irror
Q. I! ra%is ! cr-atre ! a cnca-e mirrr is 1m (hat is its !ca" "en#th$
&ns Ii3en:? Ra*i/s R 1+ &euired:?
oca en-th ,M #olution:?
&s .e ;no. that R82 /ttin- the 6a/e ,W , 0 + Q2. 7r (hat 'sitin ! an b:ect a cnca-e mirrr !rms an% ima#e (hich is rea" an% e<a" in siBe t the b:ect$
&ns I, an oJect is pace* at centre o, c/r6at/re o, a conca6e +irror then rea5 in6erte* i+a-e is ,or+e* .hich is e
Q4. 7r (hat 'sitin ! an b:ect a rea" an% %iminishe% ima#e is !rme% by a cnca-e mirrr$
&ns .hen an oJect is pace* eyon* centre o, c/r6at/re o, a conca6e +irror then rea5 in6erte* an* *i+inishe* i+a-e is ,or+e* et.een centre o, c/r6at/re @CA an* principa ,oc/s @A
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
=E NORTH HILLS SCHOOL COLL!"!
Q8. Gi-e at "east three ses ! cnca-e mirrr$
&ns. 0ses ! cnca-e mirrr :9 i ii iii
& si+pe conca6e +irror is /se* y *octors to ea+ine nose5 throat an* ear Conca6e +irror is /se* in +icroscope to concentrate i-ht on +icroscope si*e Conca6e +irror o, ar-e apert/re is /se* in teescope to oser6e *istant oJects on earth an* hea6eny o*ies
Q9. De3ne re!racti-e in%e&. H( it is re"ate% t -e"city ! "i#ht in a 'air ! me%ia.
&ns Re,racti6e In*e:9 The re,racti6e in*e is the ratio o, the 6eocity o, i-ht in the air an* 6ac//+ to the 6eocity o, i-ht in -i6en +e*i/+ Th/s the re,racti6e in*e o, -ass .ith re,erence to air is -i6en y '
=
#ocit of #i%ht in ai! #ocit of #i%ht in %#ass
⇒' =
c v
s The re,racti6e in*e o, a s/stance *oes not *epen* on the an-e o, inci*ence /t *epen*s on the nat/re o, the +ateria o, the +e*i/+ Re,racti6e in*e is a ratio et.een t.o si+iar
&ns The rays o, i-ht passin- thro/-h the ,oc/s point o, a conca6e +irror eco+e parae to the principa ais a,ter reection There,ore the rays o, i-ht can e +a*e parae to the principa ais o, a conca6e +irror y pacin- the / at principa ,oc/s o, a conca6e Q1=. Which ty'e ! s'herica" mirrr has a (i%e"y 3e"% ! -ie($
&ns The con6e +irror has a .i*er e* o, 6ie. eca/se it pro*/ce 6irt/a5 erect an* *i+inishe* i+a-e o, an oJect pace* in ,ront o, it Q11. Why %es a %ri-er 're!er t se a cn-e& mirrr as a bac -ie( mirrr in an atmbi"e$
&ns & *ri6er pre,er to /se a con6e +irror as a ac; 6ie. +irror in an a/to+oie eca/se it pro6i*es a .i*er e* o, 6ie. ehin* the 6ehice an* heps the *ri6er to *ri6e sa,ey Q1+. A ray ! "i#ht tra-e""in# in (ater emer#es int air. Dra( a ray %ia#ram in%icatin# the chan#e in its 'ath$
&ns #e ;no. that a ray o, i-ht enterin- ,ro+ *enser to rare +e*i/+5 it en*s a.ay ,ro+ the nor+a Th/s in the -i6en -/re the inci*ent ray &O enterin- ,ro+ .ater to air chan-e its path a ray OC en*in- a.ay ,ro+ the nor+a The an-e o, inci*ence is ,or+e* in .ater is ess than an-e o, re,raction
∠
r in the air i9e
∠ ∠ iU
r
Q1/. What is nit ! re!racti-e in%e&$
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
=G NORTH HILLS SCHOOL COLL!"!
&ns &s re,racti6e in*e is -i6en y η =
sin ∠i sin
∠r
Or
n C87 #hich sho.s the re,racti6e in*e is a ratio et.een t.o si+iar
&ns Re,racti6e in*e o, .ater is 133 i9e n. 133 .hie the re,racti6e in*e o, a -ass is 1KE i9e n- 1KE there,ore re,racti6e in*e o, a -ass is -reater than that o, .ater Q12. De3ne Sne""s "a( ! re!ractin$
&ns in 1E205 Sne presente* the a. o, re,raction .hich is -i6en @ratio o, sinX o, an-e o, inci*ence to the sinX o, an-e o, re,raction is constant ,or -i6en pair o, +e*iaA Mathematically :
η =
∠i sin ∠r sin
#here @nA represents the re,racti6e in*e o, the secon* +e*i/+ .ith respect to the rst +e*i/+ Q14.Why a 'enci" ha"! immerse% in (ater an% he"% b"i<e"y5 a''ears t be bent at the (ater sr!ace$
&ns The i/sion is ca/se* eca/se o, re,raction o, i-ht The i-ht rays co+in- ,ro+ the o.er en* o, the penci i9e ,ro+ point @BA an* passes ,ro+ .ater into air &B the ray enters into rare +e*i/+ ,ro+ a *enser +e*i/+5 so the ray en*s a.ay ,ro+ the nor+a On enterin- the eye the rays appear to e co+in- ,ro+ point @C’ ao6e point B as sho.n in -/re
Th/s point @CA represent the i+a-e at point @BA */e to re,raction Th/s the oser6er sees the i+a-e apparenty in the position @&CA an* as a res/t the penci appears to e ent at the .ater s/r,ace Y1G. 7r (hat 'sitins ! an b:ect a rea"5 %iminishe% ima#e is !rme% by a cnca-e "ens$ &ns .hen the oJect @&BA is pace* eyon* 2 in ,ront o, con6e ens then a rea5 in6erte* an* a *i+inishe* i+a-e is ,or+e* et.een an* 2
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
= NORTH HILLS SCHOOL COLL!"!
Q19. What is SI nit ! a '(er ! a "ens$
&ns The SI /nit o, po.er o, a ens is *ioptre The po.er o, ens is *ene* as @The reciproca o, ,oca en-th in +etersA The po.er o, a ens is *enote* By @A an* is -i6en y
18 , (+eter)
The po.er o, ens is sai* to e one *ioptre i, the ,oca en-th o, a ens I 1+ Q1;. What (i"" be the -a"e ! an#"e ! re!ractin (hen the an#"e ! inci%ence in %enser me%im is e<a" t the critica" !r a #i-en 'air ! me%ia$
&ns as .e ;no. that critica an-e is the an-e o, inci*ence in *enser +e*i/+ ,or .hich the an-e o, re,raction in rare +e*i/+ eco+es K0 There,ore .hen the 6a/e o, an-e o, inci*ence in *enser eco+es e
Q+=. Why % stars t(in"e n a c"ear ni#ht$
&ns the i-ht ,ro+ the stars tra6e thro/-h *iDerent ayers o, the at+osphere o, 6aryin- *ensities There,ore the i-ht rays *e6iate ,ro+ its ori-ina path /rther these ayers are not stationary5 /t ;eep on +o6in- These reasons ea* to the t.in;in- eDect o, the stars
Q+1. F are #i-en t( cn-e& "enses ! !ca" "en#th 8cm an% += cm. (hich ne (i"" y chse as b:ecti-e "ens !r main# a cm'n% micrsc'e$
&ns .e ;no. that the +a-ni,yin- po.er o, co+po/n* +icroscope is -i6en y M
=
d 1 + ) o f e *o
In e
Chapter No: 12 #RITT!N B$: %&HOOR &H'&
=K NORTH HILLS SCHOOL COLL!"!
Th/s i, .e /se a conca6e ens5 then the +a-ni,yin- po.er o, co+po/n* +icroscope .i increase Q++. What ty'e ! "ens is se% t mae the eye 'iece ! cm'n% micrsc'e$
&ns The eye piece o, co+po/n* +icroscope is a con6e ens ha6in- co+parati6ey ar-er apert/re an* ,oca en-th as co+pare to oJecti6e ens Q+/. In a te"esc'e5 (hich ne has a shrter !ca" "en#th5 the b:ecti-e r the eye 'iece$
&ns .e ;no. that the +a-ni,yin- po.er o, teescope is -i6en y ' ,o8,e 999999999999999999999 (i) !
Q+. Writin# n the b"ac bar%$ a Name the ty'e ! %e!ect !rm (hich he is serin#$ b With the he"' ! ray %ia#ram5 sh( h( this %e!ect can be reme%ie%$
&ns a
The *e,ect ,ro+ .hich the chi* is s/Derin- is cae* short si-hte*ness or 'yopia or the correction o, these *e,ects5 a conca6e ens is pace* in ,ront o, the eye This co+ination o, t.o enses enaes the i+a-e to e retina
CH&T!R NO 13 a - e Z 1J
N O RT H H I L L S S C H O O L C O L L ! " !
Electrostatics Electricity:
The ranch o, physics .hich *eas .ith the st/*y o, char-es at rest or in +otion is cae* eectricity There are t.o ranches o, eectricity .hich are as ,oo.s4 1 !ectrostatics or static eectricity 2 !ectro*yna+ics or c/rrent eectricity $. Electrostatics:( !ectro +eans char-e an* static +eans rest)
The ranch o, physics .hich *eas .ith the st/*y o, properties o, char-es at rest is ;no.n as eectrostatics or static eectricity 2 Electrodynamics: ( !ectro +eans char-e an* *yna+ics +eans +otion) The ranch o, physics .hich *eas .ith the st/*y o, properties o, char-es in +otion is cae* eectro*yna+ics or c/rrent eectricity Electric charge:
!ectric char-e is the physica property o, +atter that ca/ses it to eperience a ,orce .hen cose to other eectricay char-e* +atter OR Char-e is the intrinsic property associate* .ith +atter */e to .hich it pro*/ces an* eperiences eectrica an* +a-netic eDects E!planation:
The eistence an* nat/re o, char-e can e /n*erstoo* y per,or+in- the ,oo.in- eperi+ents4 E!periment $: #hen an /nchar-e* -ass ro* is ro/-ht near a s/spen*e* pith a
as sho.n in the -/re The pith a re+ains in its rest position sho.in- that the -ra6itationa ,orce o, attraction et.een the pith a an* the /n char-e* -ass ro* is too .ea; to ca/se any +o6e+ent in the pith a
E!periment *: #hen a -ass ro* is r/e* .ith si; coth an* ro/-ht near the
s/spen*e* pith a The a is seen to +o6e to.ar*s the -ass ro* sho.in- that -ass ro* r/e* .ith si; coth has the aiity to attract s+a oJects Th/s .e say that -ass ro* is char-e*
E!periment -: #hen an eonite ro* is r/e* .ith ,/r is
ro/-ht near a s/spen*e* pith a The a is seen to +o6e to.ar*s the eonite ro* sho.in- that the eonite
CH&T!R NO 13 a - e Z 1$
N O RT H H I L L S S C H O O L C O L L ! " !
ro* is ae to attract i-ht oJects .hen r/e* .ith ,/r Th/s the eonite ro* is char-e* E!periment : .hen a char-e* -ass ro* is ro/-ht near a s/spen*e* char-e*
-ass ro* The t.o -ass ro*s repe each other sho.in- that @i;e char-es repe each otherA
E!periment 1: .hen a char-e* -ass ro* is ro/-ht near a s/spen*e* char-e*
pastic ro* The t.o ro*s attract each other sho.in- that @/ni;e char-es attract each otherA
Electric nature of matter:
In -enera5 the +atter is eectricay ne/tra The a+o/nt o, positi6e char-es an* ne-ati6e char-es are e
The s+aest partice o, +atter .hich can or cannot eist ,ree in nat/re is ;no.n as ato+ &n ato+ consists o, t.o parts4 the centra +assi6e part is cae* n/ce/s .hich has positi6e char-e consistin- o, protons an* ne/tron The proton 1 × 10 −2 !%
has +ass o, .hie the +ass o, ne/tron is ess than that o, proton rotons an* ne/tron are coecti6ey ;no.n as n/ceons The char-e on each proton is e
+ 1 ×10−15 ,
!ectrons are the thir* partices .hich are re6o6in- aro/n* the n/ce/s in 511× 10 −31 !%
circ/ar orits The +ass o, eectron is
an* the char-e on eectron is
− 1 ×10 −15 ,
In a nor+a con*ition the n/+er o, eectrons an* n/+er o, protons are e
Methods of charging an obHect:
There are t.o +etho*s */e to .hich an oJect can e char-e* a Char-in- y r/in-
!ectrostatic In*/ction
a. 2harging by rubbing:
The process in .hich t.o ne/tra oJects can e char-e* y r/in- it .ith one another is ;no.n as char-in- y r/in-
CH&T!R NO 13 a - e Z 1*
N O RT H H I L L S S C H O O L C O L L ! " !
E!planation:
#hen -ass ro* is r/e* .ith si; coth5 so+e eectrons ,ro+ the s/r,ace ato+s o, -ass ro* are trans,erre* to si; coth This +a;es -ass ro* positi6ey char-e* as it is no. short o, eectrons The si; coth eco+es ne-ati6ey char-e* as it -ains ecess o, eectrons
Electrostatic induction:
The process5 in .hich a char-e o*y chan-es the char-e *istri/tion o, a neary ne/tra o*y5 is ;no.n as eectrostatic in*/ction E!planation:
#hen a char-e* o*y is ro/-ht near y a ne/tra o*y then the ne-ati6e an* positi6e char-es o, ne/tra o*y rearran-es the+se6es on the s/r,ace as .e as in the interior o, the o*y This eDect is ;no.n as eectrostatic in*/ction This process occ/rs in ins/ator as .e as in con*/ctor The ne/tra o*y re-ains its ori-ina state .hen the char-e* o*y is re+o6e*
2harging an insulator by induction:
#hen a char-e* co+ is ro/-ht near a ne/tra ins/ator5 the ato+s o, the ins/ator in*/ce itse, in s/ch a .ay that partia positi6e char-e is pro*/ce* on one en* o, the ato+ an* partia ne-ati6e on the other en* ,or+s a *ipoe as sho.n in the -/re One *ipoe in*/ces another *ipoe This pheno+enon is ;no.n as poari?ation In this .ay the co+ attracts the ins/ator to.ar*s itse,
2harging by conductor by induction:
Consi*er a +etaic sphere pace* on ins/atin- .oo*en stan* as sho.n in the -/re #hen a positi6ey char-e* ro* is ro/-ht near the sphere5 then the char-e *istri/tion o, the sphere chan-es an* the ,ree eectrons o, the sphere .i arran-e the+se6es coser to the ro* The
CH&T!R NO 13 a - e Z 1-
N O RT H H I L L S S C H O O L C O L L ! " !
Elecroscope:
It is an instr/+ent /se* ,or *etectin- an* testin- the nat/re o, char-e on a o*y 2onstruction:
& si+pe eectroscope consists o, a +eta ro*5 .hich has +etaic *isc at its /pper en* .hie its o.er en* is attache* to -o* ea6es as sho.n in the -/re The ro* is e* in a -ass Jar
2harge 0etection:
The presence o, char-e on a o*y can e *etecte* y rin-in- it near the *isc o, an /nchar-e* eectroscope as sho.n in the -/re I, the o*y is char-e* then the ea6es o, the eectroscope .i *i6er-e to a *enite etent5 other.ise they .o/* re+ain in their nor+a position Th/s the presence o, char-e can e *etecte* ,ro+ the *i6er-ence o, ea6es o, eectroscope */e to eectrostatic in*/ction Testing the nature of charge:
or testin- the nat/re o, char-e on a o*y .e rst nee* to char-e the eectroscope either positi6ey or ne-ati6ey y to/chin- its *isc .ith positi6ey or ne-ati6ey char-e* o*ies /e to char-in- the ea6es o, the eectroscope *i6er-e to certain etent I, a char-e* o*y is ro/-ht near the *isc o, the char-e* eectroscope an* the *i6er-ence o, ea6es increases it has sa+e char-e as that on the eectroscope I, the *i6er-ence o, the ea6es *ecreases then it has opposite char-e to that o, the eectroscope
2oulombFs la5:
In 1G5 Chares co/o+ a rench physicist per,or+e* 6ario/s eperi+ents an* ,o/n* that the ,orce et.een t.o char-e o*ies *epen*s on *istance et.een char-es an* +a-nit/*e o, char-es He state* it in the ,or+ o, co/o+’s a. #tatement:
@The ,orce o, attraction or rep/sion et.een any t.o o*ies is *irecty proportiona to the pro*/ct o, char-es an* in6ersey proportiona to the s
*1
*2
Consi*er t.o point char-es an* pace* at a *istance >r’ ,ro+ one another as sho.n in the -/re &ccor*in- to co/o+’s a.5 the ,orce o, attraction or rep/sion et.een the+ is -i6en y the reations
CH&T!R NO 13 a - e Z 1
∝
"
∝
"
N O RT H H I L L S S C H O O L C O L L ! " !
*1 *2 − − − − − − − −1 1
−−−−−−−−−−−2
r 2
Co+inin- e
∝
"
=
*1 * 2 !
r 2 *1 * 2
−−−−−−−−−3
r 2
!
#here @
A is constant o, proportionaity ;no.n as co/o+’s constant The 6a/e o,
!
@ A*epen*s /pon the nat/re o, +e*i/+ an* syste+ o, /nits in .hich 5 < an* r are +eas/re* I, the +e*i/+ is ,ree space an* syste+ o, /nits is SI5 then the 6a/e o, !
is -i6en y !
=
1
=
4π ε o
5
×
105
$ m , 2
66& × 10
ε o
#here @
A is per+itti6ity o, ,ree space an* its 6a/e is
−12
, 2 $ m
By
!
s/stit/tin- the 6a/e o, "
=
.e can aso .rite e
*1 * 2
4π ε o
r 2
Co/o+’s a. is 6ai* ,or point char-es in .hich the si?e o, char-e o*ies is s+a as co+pare* to the *istance et.een the+ 2oulombFs la5 in dielectric:
&n ins/atin- +ateria (other than air or 6ac//+) ;no.n as *ieectric pace* in et.een the point char-es the ,orce et.een the char-es is re*/ce* y ε r
,actor
;no.n as *ieectric constant or reati6e per+itti6ity The 6a/e o, *ieectric
constant is *iDerent ,or *iDerent *ieectrics The ,orce constant is -i6en y " /
=
1
*1* 2
4πε o ε r
r 2
9nit of charge:
The SI /nit o, char-e is co/o+ 2oulomb:
" /
in presence o, *ieectric
CH&T!R NO 13 a - e Z 11
N O RT H H I L L S S C H O O L C O L L ! " !
One co/o+ is the a+o/nt o, char-e .hich repes an e
×10 5 $
char-e .ith a ,orce o,
pace* in air at a *istance o, 1 + ,ro+ each other
Electric Aeld:
The space or re-ion aro/n* a char-e .here it eperiences eectric ,orce on test char-es is ;no.n as eectric e* E!planation:
The re-ion or space aro/n* the char-e .here it possesses specia properties an* eperience eectric ,orce on other char-es is ;no.n as eectric e* or ,orce e* It is a 6ector e* Electric Aeld intensity:
The eectric e* intensity at a point is *ene* as4 @The ,orce eperience* on a /nit positi6e test char-e pace* at a point .ith in the eectric e*A Mathematically:
Consi*er a ,orce
"
+* is actin- on a test char-e
at a point .ith in
&
the eectric e*4 then the eectric e* intensity
&
=
at that point is -i6en y
"
+*
!ectric e* intensity is a 6ector
.hich the test char-e .i +o6e The /nit o, eectric e* intensity is
Electric lines of force:
The aritrary ines /se* to represent the *irection an* +a-nit/*e o, eectric e* is ;no.n as eectric ines o, ,orce "roperties of electric lines of force:
1 The ines o, ,orce are *irecte* o/t.ar* ,or positi6e char-e an* in.ar* ,or
ne-ati6e char-e 2 The e* pattern o, set /p y the t.o e
CH&T!R NO 13 a - e Z 1=
N O RT H H I L L S S C H O O L C O L L ! " !
3 The e* pattern o, set /p y the t.o e
= The eectric e* et.een the t.o oppositey char-e* parae pates is /ni,or+ at the centra re-ion as sho.n in the -/re No t.o ines intersect each other
Electrostatic potential:
The .or; *one in rin-in- a /nit positi6e char-e ,ro+ a point o, innity to a point .ith in the eectric e* is ;no.n as eectrostatic potentia at that point Mathematically:
I, # is the a+o/nt o, .or; *one in rin-in- a test char-e [< ,ro+ innity to a certain point in the e*5 the potentia 7 at that point .o/* e -i6en y -
=
W
+*
"otential di7erence:
otentia *iDerence et.een t.o points is *ene* as the .or; *one in +o6in- a /nit positi6e char-e ,ro+ one point to another a-ainst the eectric e* Mathematically:
- (
−
- A
=
W A(
+*
!ectric potentia is a scaar
#hen one Jo/e .or; is *one in rin-in- a /nit positi6e char-e ,ro+ a point to another point .ith in the eectric e* then the potentia at that point .i e one 6ot 2apacitor:
The *e6ice /se* ,or the stora-e o, eectric char-e is cae* capacitor
CH&T!R NO 13 a - e Z 1G
N O RT H H I L L S S C H O O L C O L L ! " !
2onstruction:
& si+pe capacitor consists o, t.o parae +etaic pates separate* y a s+a *istance as sho.n in the -/re &ir or an ins/atin- +e*i/+ cae* *ieectric is pace* in et.een the pates
2harging a capacitor:
The capacitor can e char-e* y pacin- one o, the pates .ith the positi6e ter+ina o, the attery .hie the other is connecte* to the ne-ati6e ter+ina o, the attery Char-e [Y an* QY appears on the pates These char-es attract each other */e to +/t/a attraction an* th/s re+ain on the s/r,ace o, the pates a,ter the re+o6a o, the attery
2apacitance of a capacitor:
The aiity o, the capacitor to store char-e is ;no.n as capacitance o, a capacitor E!planation:
It is eperi+entay ,o/n* that the char-e Y on the pate o, a capacitor is *irecty proportiona to the eectric potentia *iDerence 7 et.een the+
7
∝ =
C
⇒
C
=
7
O 7
#here >C’ is constant o, proportionaity ;no.n as capacitance o, the capacitor The 6a/e o, >C’ *epen*s /pon the area o, the pates5 *istance et.een the+ an* the +e*i/+ et.een the+ 9nit of capacitance:
The SI /nit o, capacitance is ,ara* #hich is *ene* as @the capacity o, that capacitor .hich stores a char-e o, 1 co/o+ y appyin- 1 6ot potentia *iDerence et.een the patesA
2ombination of capacitors:
CH&T!R NO 13 a - e Z 1@
N O RT H H I L L S S C H O O L C O L L ! " !
The connection o, capacitors in eectrica circ/it is ;no.n as co+ination o, capacitors The capacitor can e connecte* either in series or in parae #eries combination of capacitors:
In series co+ination o, capacitors5 the capacitors are connecte* pate to pate as sho.n in the -/re The ri-ht pate o, one capacitor is connecte* to the e,t pate o, the net capacitor so on In series co+ination a the capacitors ac
2haracteristic features:
Consi*er three capacitors are attache* to one another in series as sho.n in the -/re 1 The attery s/ppies [Y to the e,t pate o, the capacitor C 1 /e to eectrostatic in*/ction QY char-e is in*/ce* on its ri-ht pate an* [Y char-e on the e,t pate o, capacitor C 2 as sho.n in the -/re Th/s the char-e on each capacitor is sa+e i9e Y 2 The s/+ o, potentia *iDerence across each capacitor 7 15 725 73 is e
=
+ =
1
As
7
3 − − − − − − − 1
2 C 7
⇒ =
C 7
1
=
2
=
3
=
C1 7 C2 7 C3
/ttin- a the 6a/es in e
,
.
=
, 1
+
. , 2
1 + , 1
=
.
=
1
, 1
+
+ 1
, 2
, 3 1
+
, 2
1
.
+
, 3
1
, 3
Let @CeA e the e
, e
=
1
, 1
+
1
, 2
+
1
, 3
3 or >n’ capacitors the ao6e e
CH&T!R NO 13 a - e Z 1B
N O RT H H I L L S S C H O O L C O L L ! " !
1
, e
=
1
1
+
, 1
+
, 2
1
, 3
+
1
, n
= The e
In parae co+ination o, capacitors5 a the e,t pates o, a the capacitors are connecte* to one point .hie the ri-ht pates are connecte* to the other as sho.n in the -/re & attery o, >7’ 6ots is appie* to the oth points In parae co+ination o, capacitors5 the potentia *iDerence across each capacitor is the sa+e .hie the char-e store* in each capacitor is *iDerent
2haracteristic features:
1 In this type o, capacitor the potentia *iDerence across each capacitor is sa+e ie - = - 1
=
- 2
= - 3 − − − − − − − 1
2 The char-e Y -i6en at point & is *istri/te* o6er a the capacitors ie .
=
.1
+
.2
+
.3 − − − − − − − 1
. = , -
&s .1 .2 .3
= = =
, 1 - 1 , 2 - 2 , 3 - 3
There,ore /ttin- in ao6e e
= , 1 - + , 2 - + , 3 - , - = ( , 1 + , 2 + , 3 ) - , = , 1 + , 2 + , 3 − − − − − − − 2 , -
3 or >n’ capacitors .e can .rite e
= The e
0i7erent types of capacitors:
Capacitors are cassie* into 6ario/s types *epen*in- /pon their constr/ction an* nat/re o, *ieectric /se* in the+ Here .e .i *isc/ss the type o, capacitors ase* on capacity $. i!ed capacitor:
CH&T!R NO 13 a - e Z =J
N O RT H H I L L S S C H O O L C O L L ! " !
Those capacitors .hose pates are i++o6ae are ;no.n as e* capacitors The capacitance o, s/ch capacitors re+ains constant an* cannot e 6arie* or ea+pe paper capacitor5 oi5 +ica or eectroyte *. )ariable capacitor:
The capacitors in .hich the area o, the pates ,acin- each other can e chan-e* are ;no.n as 6ariae capacitors The capacitance o, s/ch capacitors *oes not re+ain constant an* can e 6arie* or ea+pe4 the capacitors /se* in the t/nin- o, ra*io
"ractical applications of electrostatics:
The practica appications o, eectrostatics are as ,oo.s4 $. Electro painting:
!ectrostatic is /se* in appyin- paints on the s/r,aces o, *iDerent artices s/ch as re,ri-erators5 +etaic ,/rnit/re5 cars etc it has eco+e a stan*ar* technoo-y or this p/rpose the o*y is earthe* eectricay The partices o, the paint e+er-in- o/t o, the no??e o, the sprayin-5 they ac
!ectrostatic pheno+enon is /se* ,or the separation o, s+o;e an* */st partices ,ro+ air co+in- o/t o, 6ario/s in*/stries Hi-hy positi6ey char-e* #ire -a/?e is e* et.een t.o +etaic pates .hich are -ro/n*e* /e to eectrostatic in*/ction ne-ati6e char-es are in*/ce* on the inner s/r,ace o, the +etaic pates The -as containin- */st an* s+o;e partices eco+e ioni?e* a,ter passin- thro/-h the -a/?e .hich is trappe* y the ne-ati6ey char-e* pates Th/s the */st an* s+o;e partices are separate* ,ro+ the air
2O(2E"T9'6 9E#T%O(#: $. ' balloon is negati3ely charged by rubbing and then clings to the 5all. 0oes this mean that the 5all is positi3ely charged; 4hy does the balloon e3entually fall; 'ns. & ne-ati6ey char-e* aoon rst cin- to the .a5 eca/se */e to its eectric
e* the point o, contact on the .a poari?e* positi6ey */e to eectrostatic in*/ction an* attract the aoon */e to eectrostatic ,orce o, attraction an* th/s cin-s Later on the aoon is ne/trai?e* eca/se the .a is -ro/n*e* an* */e to -ra6ity the aoon e6ent/ay ,as *. 4hy is it not a good idea to seek shelter under a tree during a lightning storm;
#hen char-e* co/*s pass o6er a ta tree5 then an opposite char-e is in*/ce* on the ta tree */e to pheno+enon o, eectrostatic in*/ction &s a res/t eectrostatic ,orce o, attraction eist et.een the tree an* the co/*s */e to .hich there is a -reater possiiity o, ,or i-htnin- *ischar-e to ta;e pace et.een the 'ns:
CH&T!R NO 13 a - e Z =$
N O RT H H I L L S S C H O O L C O L L ! " !
tree an* the co/*s There,ore it is not a -oo* i*ea to see; sheter /n*er a tree */rin- a i-htnin- stor+ -. ' charged comb often attracts small bits of dry paper that then 8y a5ay 5hen they touch the comb. E!plain;
#hen co+ is ro/-ht near the its5 */e to poari?ation5 its -ets oppositey char-e*5 hence they are attracte* y the co+ #hen they to/ch the co+5 at point o, contact the char-e is ne/trai?e* /t the ,/rther points on the co+ an* its ha6e si+iar static char-es so */e to rep/sion y a.ay 'ns:
. 0eAne the term 3olt; 'ns: 7ot is the SI /nit o, potentia *iDerence It is *en e* as4
@I, one Jo/e o, .or; is *one in carryin- one co/o+ o, char-e ,ro+ one point to another a-ainst the eectric e*5 then the potentia *iDerence et.een these t.o points .i e one 6ot Mathematically: 1"
=
1+ 1C
1. 4hat is meant by charging of an obHect electrically; 'ns: #hen positi6e an* ne-ati6e char-e appears on a o*y5 it +eans that the
oJect is char-e* eectricay #hen the n/+er o, protons an* eectrons in an oJect are e
=. T5o isolated copper spheres ', K are initially uncharged. They are placed near each other as sho5n in the Agure. 4hat is the charge distribution on ' 5hen K is gi3en a negati3e charge; 'ns: #hen the ne-ati6e char-e* sphere >B’ is ro/-ht near ne/tra sphere >&’5 then
char-e is in*/ce* on sphere & */e to eectrostatic in*/ction The positi6e char-es on sphere & are arran-e* on the si*e .hich is coser to & .hie the ne-ati6e char-es are arran-e* to the e,t si*e o, the sphere as sho.n in the -/re
G. 4hy electric charge is produced on bodies by friction; 'ns: #hen t.o o*ies are r/e* to-ether5 then eectrons are trans,erre* ,ro+ one
o*y to another */e to ,riction The o*y .hich oses eectrons eco+es positi6ey char-e* .hie the o*y .hich -ain eectron eco+es ne-ati6ey char-e*
CH&T!R NO 13 a - e Z =*
N O RT H H I L L S S C H O O L C O L L ! " !
1 µ "
001 µ "
@. T5o capacitors 5ith capacitance and are charged to the same potential; 4hich 5ill gi3e more intense shocked if touched; 'ns: Ii3en data:
= 1 µ " = 1 × 10 − " = 10 − " , 2 = 001 µ " = 001 × 10 − " = 10 −6 " - 1 = - 2 = - , 1
&so .e ;no. that4 .1
=
, 1 -
.2
=
, 2 -
an*
/ttin- the 6a/es .e -et4 .1
=
10 − -
.2
=
10 −6 -
an* .1
> .2
ro+ ao6e e
B. 's sho5n in the Agure a chain hanging from the rear side of the petrol supply tanker. 4hat is its purpose; 'ns: etro is hi-hy ina++ae /i* The chain sho/* e to/chin- the -ro/n* to
;eep tan;er’s o*y at ?ero potentia an* a6oi* a spar; *ischar-e */e to .hich petro can catch re $J. The tyres of an aircraft are made from special rubber that conducts electricity. E!plain 5hy; 'ns: &ircra,t’s .hen +o6in- in air .ith hi-h spee* eco+e char-e* */e to ,riction
*/e to ,riction .ith air +oec/es an* .ith 6ario/s co/* #hen the aircra,t is an*in- an* to/ches the -ro/n*5 the char-es o.s to the -ro/n* thro/-h tyres5 the aircra,t o*y eco+es ne/tra an* th/s a6oi*s the spar;in- In this .ay the aircra,t re+ains in sa,e an* so/n* con*ition
4ritten by: Cahoor 'hmad M.#c "
CH&T!R NO 13 a - e Z =-
N O RT H H I L L S S C H O O L C O L L ! " !
E= CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
2<'"TE& (O: $
CURRENT ELECTRICITY
2urrent electricity or Electrodynamics:
The ranch o, eectricity .hich *eas .ith the st/*y o, eectric char-es in +otion is ;no.n as 2urrent electricity. The st/*y o, c/rrent eectricity is +ore i+portant than eectrostatics5 eca/se it has +ore appications in o/r *aiy i,e Electric current:
The rate o, o. o, c/rrent thro/-h any cross sectiona area o, a con*/ctor is cae* eectric c/rrent E!planation:
I, char-es >Y’ passes thro/-h any cross sectiona area >&’ in ti+e >t’ secon*s Then the c/rrent >I’ o.in- thro/-h it is -i6en y e
=
. t
!ectric char-es are o, t.o ;in*s5 positi6e an* ne-ati6e So eectric c/rrent is pro*/ce* */e to the o. o, ne-ati6e or positi6e char-es or oth In con*/ctors it is */e to the o. o, ,ree eectrons ie ne-ati6e char-es In n/cear acceerators5 c/rrent o. */e to the positi6e char-es .hie in eectroytes5 it is */e the o. o, oth positi6e an* ne-ati6e char-es 9nit of electric current:
The SI /nit o, eectric c/rrent is a+pere 'mpere:
#hen 1 co/o+ char-e o.s in cross sectiona area o, a con*/ctor in /nit ti+e the c/rrent passin- thro/-h it is 1 a+pere 1 A
=
1, 1 s
2on3entional current:
The eectric c/rrent pro*/ce* */e to o. o, positi6e char-es is ;no.n as con6entiona c/rrent The *irection o, con6entiona c/rrent is ,ro+ positi6e to.ar*s ne-ati6e ter+ina o, a attery
E!planation:
!ary scientists tho/-ht that c/rrent is */e to o. o, positi6e char-es /t to*ay it is .e ;no.n that in +etas or 6ac//+ t/es the c/rrent is */e to o. o, ,ree eectrons ie ne-ati6e char-es In eectroytes c/rrent is pro*/ce* */e to the o. o, oth positi6e an* ne-ati6e char-es an* in n/cear reactor it is */e to the o. o, positi6e char-es (protons) The positi6e char-e +o6in- in one *irection is e
E CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
OhmFs la5:
In 12E5 "er+an scientist "eor-e Si+on Oh+ a,ter per,or+in- se6era eperi+ents n* a reation et.een c/rrent o.in- in a con*/ctor an* the 6ota-e appie* across the en*s o, the con*/ctor He state* it in the ,or+ o, oh+’s a. #tatement:
@The c/rrent o.in- thro/-h an eectrica con*/ctor is *irecty proportiona to the 6ota-e appie* across the en*s o, the con*/ctor y ;eepin- the te+perat/re an* other physica con*ition constantA Mathematically:
I ∝
⇒I = ⇒
1
( Phsica# stat an$ Tm8!at9! = constant) 1
= I
= Constant
/
#here
is constant o, proportionaity an* is cae* resistance o, the con*/ctor
6imitation of OhmFs la5: Ohmic conductors or linear conductors:
The con*/ctors .hich oey Oh+’s a. are ;no.n as Oh+ic con*/ctorsi9 I∝
e !a+pes o, Oh+ic con*/ctors are +etas an* so+e aoys at constant te+perat/re Metallic conductors:
#hen .e pot I97 -raph o, +etaic con*/ctors at constant 1
te+perat/re5 it -i6es strai-ht ine .ith a sope o, as sho.n in the -/re The resistance o, the Oh+ic con*/ctor *oes not chan-e .hen the potentia *iDerence across it chan-es5 y ;eepin- the te+perat/re constant (on?Ohmic conductors:
The con*/ctors .hich *o not oey Oh+’s a. are ;no.n as non9Oh+ic con*/ctors The I97 -raph o, s/ch +ateria is noninear or ea+pe a+ent o, an eectric /5 ther+istors an* *io*es etc ilament of an electric bulb:
The I97 -raph ,or a a+ent en*s o6er as I an* 7 increases as sho.n in the -/re This +eans that the sope *ecreases .ith increase o, 6ota-e an* is not a strai-ht ine Th/s the resistance o, the t/n-sten .ire a+ent
EE CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& increases as the c/rrent rises its te+perat/re an* +a;e it .hite hot Thermistor:
& ther+istor is a type o, resistor .hose resistance 6aries si-nicanty .ith te+perat/re The I97 -raph o, ther+istor en*s /p.ar* as sho.n in the -/re This +eans that the resistance *ecreases sharpy .ith the rise in te+perat/re Ther+istors are +a*e /p o, se+icon*/ctors
&esistance:
The property o, a s/stance to oppose the o. o, c/rrent passin- thro/-h it is cae* resistance Mathematically:
#hen potentia *iDerence I
*/e to .hich c/rrent -i6en y
is appie* across the en* o, a con*/ctor
o.s thro/-h it The resistance
R
=
R
oDere* y the con*/ctor is
I
E!planation:
It can e seen that i, the 6a/e o, resistance
R
is increase* ,or a certain
6a/e o, potentia
then the 6a/e o, c/rrent .o/* e s+a It +eans that the R
opposition to the o. o, c/rrent .o/* e ar-e On other han*5 i, is s+a then the opposition to the o. o, c/rrent .i e s+a an* ar-e c/rrent .i o. thro/-h the +ateria Th/s
R
is the +eas/re o, resistance o, the con*/ctor
9nit:
The SI /nit o, resistance is oh+ represente* y "ree; etter o+e-a (
Ω
)
Ohm:
The resistance o, a con*/ctor .i e one oh+ .hen one 6ot potentia *iDerence is appie* across its en*s an* the c/rrent o.in- thro/-h it is one a+pere 1Ω
=
1 1A
#peciAc resistance or resisti3ity:
EG CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& The resistance o, a +ateria o, /nit en-th ha6in- /nit area o, cross9 section E!planation:
&s .e ;no. that in a con*/ctor eectrons *o not +o6e in strai-ht ine path /t they repeate*y coi*e .ith the +eta ato+s &t certain te+perat/re the resistance o, a con*/ctin- .ire *epen*s /pon its en-th5 area o, cross section an* nat/re o, the +ateria La.s o, resistance states that5 the resistance o, a con*/ctor is 1 irecty proportiona to its en-th R ∝ ' − − − − − − − 1 2 In6ersey proportiona to cross sectiona area 1 R ∝ −−−−−−−2 A Co+inin- e
∝
'
⇒ R =
ρ
R
A ' A
ρ #here (rho) is the intrinsic property o, the con*/ctor an* is ;no.n as specic resistance or resisti6ity I, L1+ an* & 1 +2 then R ρ
The SI /nit o, specic resistance is oh+9 +eter (
Ω−m
)
2ombination of resistors:
The arran-e+ent o, resistances in a circ/it .hich aDects the o. o, c/rrent thro/-h each resistor an* the 6ota-e *rop across each resistor is ;no.n as co+ination o, resistors Resistors are connecte* in t.o asic .ays4 in series an* in parae $. #eries combination of resistors:
In series co+ination the resistances are connecte* in s/ch a .ay that the o. o, c/rrent thro/-h each resistor is one a,ter the other Th/s sa+e a+o/nt o, c/rrent o. thro/-h a resistances E!planation:
R3
R1 R2
Consi*er .e ha6e three resistances
5
I
an*
e connecte* in series as
sho.n in the -/re Let e the c/rrent o.in- thro/-h the+ an* 7 e the potentia *iDerence appie* across its en*s 7 15 72 an* 73 are the potentia R3
R1 R2
*iDerences across -
=
5 - 1
an*
+ - 2 + - 3
ro+ oh+’s a. .e ;no. that
s/ch that
E CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
= I Re ⇒ - 1 = I R1 ⇒ - 2 = I R2 ⇒ - 3 = I R3 -
Re
#here is the e
+ - 2 + - 3 I Re = I R1 + I R2 + I R3 I Re = I ( R1 + R2 + R3 ) Re = R1 + R2 + R3 -
=
- 1
Hence .hen a n/+er o, resistances are connecte* in series5 the e
In parae co+ination o, resistances the resistances are connecte* in s/ch a .ay one en* o, each resistance is connecte* to one co++on point an* the other en* to the other co++on point so that there are *iDerent paths ,or the o. o, c/rrent E!planation:
R3
R1 R2
Consi*er .e ha6e three resistances
5
an*
e connecte* in
I
parae as sho.n in the -/re Let c/rrent @ A reachin- to point & *i6i*e I 3
I 1 I 2
itse, into three parts
5
an* I
R1 R2
aon-
=
I 1
+
I 2
5
R3
an*
respecti6ey s/ch that
+ I 3 − − − − − − − −1 Re
Let 7 the potentia *iDerence et.een & an* B an* resistance o, the co+ination .e ;no. ,ro+ Oh+’s a. that4 - = IR
⇒ I 1 = ⇒ I 2 = ⇒ I 3 =
- R1 - R2 - R3
/ttin- a the 6a/es in e
e e
EK CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& - R - R 1
R
=
- R1
+
- R2
+
- R3
1 1 1 =- + + R1 R2 R3 =
1
R1
+
1
R2
+
1
R3
Hence .hen a n/+er o, resistances are connecte* in parae5 then reciproca o, the e
The c/rrent .hich a.ays o. in sa+e *irection is ;no.n as *irect c/rrent E!planation:
The c/rrent .hich .e -et ,ro+ a ce or a attery is *irect c/rrent eca/se it a.ays o.s in the sa+e *irection The poarity o, *irect c/rrent is e* irect c/rrent in short ,or+ can e .ritten as C 'lternating current:
I, the c/rrent chan-es *irection a,ter e
Consi*er a resistance R .hose & en* is connecte* to the aternatin- 6ota-e so/rce .hie the B en* is earthe* (at ?ero potentia) as sho.n in the -/re
The 6ota-e at the en* & 6aries .ith ti+e is represente* y the -raph #e oser6e that the -raph et.een the ti+e inter6as 09T5 T92T5 2T93T is eacty the sa+e The ti+e inter6a a,ter .hich the 6ota-e repeats its 6a/e is ;no.n as ti+e perio* /rin- the ti+e inter6a 09T825 the potentia o, the en* & is positi6e .ith respect to en* B so in this inter6a the c/rrent o.s ,ro+ & to B It starts ,ro+ 05
G0 CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& -ra*/ay increases to +ai+/+ 6a/e an* nay *ecreases to 0 The .a6e ,or+ is cae* positi6e ha, cyce /rin- the inter6a T82 Q T5 the potentia o, en* & -ets ne-ati6e .ith respect to en* B so in this inter6a the c/rrent o.s ,ro+ B to & It starts ,ro+ 05 -ra*/ay increases to +ai+/+ 6a/e an* nay *ecreases to 0 The .a6e ,or+ is cae* ne-ati6e ha, cyce This positi6e ha, cyce an* ne-ati6e ha, cyce repeats its se6es a-ain an* a-ain in e
The path re
The co+ponents .hich are connecte* in a circ/it are ;no.n as circ/it co+ponents or ea+pe s.itches5 atteries5 resistors5 etc #5itches:
It is an eectric circ/it contro ee+ent .ith t.o *iscrete states ie on an* oD or cose* an* open &s on- as the s.itch is open no c/rrent o.s thro/-h the circ/it ha6in- innite resistance #hen the circ/it is cose* the c/rrent o. in the circ/it ha6in- ?ero resistance It is *enote* y
&esistors:
Resistors are the *e6ices .hich pro6i*e resistance so that .hen connecte* in a circ/it they re*/ce the c/rrent to a *esire* 6a/e They are +a*e /p o, .ire cois o, specia aoys or ,ro+ caron The sy+o o, resistor is
7ariae resistor is
/se* in eectronics ha6in- sy+o o, Katteries: Batteries are the *e6ices .hich +a;e a contin/o/s o. o, c/rrent in a circ/it It is a co+ination o, +any ces They con6erts che+ica or soar ener-y to eectrica ener-y an* are *enote* y
Measuring instruments: $. Ial3anometer:
"a6ano+eter is an instr/+ent y .hich .e can *etect the presence o, c/rrent in a circ/it In or*er to *etect c/rrent in a circ/it -a6ano+eter is connecte* in series I, its nee*e sho.s *eection5 it .o/* in*icate the presence o, c/rrent in the circ/it "a6ano+eter is aso /se* to *etect the c/rrent et.een t.o points in a circ/it *. 'mmeter:
&++eter is an instr/+ent .hich is /se* ,or +eas/rin- ar-e a+o/nt o, c/rrent &++eter is +o*ie* ,or+ o, -a6ano+eter & -a6ano+eter can e +o*ie* into a++eter y connectin- o. sh/nt resistance in parae In or*er to +eas/re c/rrent in a circ/it a++eter sho/* e connecte* in series -. )oltmeter:
& 6ot+eter is an instr/+ent /se* ,or the +eas/re+ent o, potentia *iDerence across t.o points in an eectrica circ/it It is connecte* in parae to the ranch across .hich the potentia *iDerence is to e +eas/re* & -a6ano+eter can e +o*ie* to 6ot+eter y connectin- hi-h sh/nt resistance in series
G1 CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& Electric energy:
The ener-y .hich .e -et */e to the o. o, eectrons is ;no.n as eectric ener-y E!planation:
Consi*er a char-e @YA passes et.een t.o points ha6in- potentia *iDerence o, @7 A 6ots #or; @#A is to e *one in +o6in- the char-e ,ro+ one point to another .hich is store* in the ,or+ o, potentia ener-y #hich is -i6en y4
⇒
;
=
;
= 7 : : : : : : : : :1
7
&so .e ;no. ,ro+ the *enition o, c/rrent ie the rate o, o. i, char-e thro/-h a con*/ctor I
=.
t ⇒ . = I t − − − − − − − −2
/ttin- in e
I, c/rrent is passin- thro/-h a resistor R an* potentia *iDerence across its en*s is 7 6ots Then ,ro+ Oh+’s a. .e ha6e4 - = I R
/ttin- in e
I
&so ,ro+ Oh+’s a. .e ;no. that
=
- R
p/ttin- in ao6e e
2
- W = R t R W =
- 2 R 2
W =
R t
- 2 t R
!ectric ener-y is -enerate* y -enerators an* ces5 .hich can e /tii?e* ,or *iDerent ,/nctions in 6ario/s resistors 9nit of energy: T he SI /nit o, ener-y is Jo/e Ho.e6er on co++ercia scae
3 × 10 <
;io.att9ho/r is /se* .hich is e
G2 CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& The rate at .hich .or; is *one in an eectric circ/it is cae* eectric po.er Mathematically:
P =
W t
− − − − −1
W = .-
&so .e ;no. that
p/ttin- in e
. - t
. ⇒ P = - t ⇒ P = I -
∴
. t
= I
W = I 2 R t
&so .e ;no. that
p/ttin- in 1 .e -et4 P =
I 2 R t t
⇒ P = I 2 R − − − − − 2 I =
- R
ro+ Oh+’s a. .e ha6e
p/ttin- in 2 .e -et4 2
- P = R R ⇒ P =
- 2 R
9nit of po5er:
The SI /nit o, po.er is .att #hort uestions $ Electric current is a 8o5 of charge, 5hy t5o 5ires rather than a single is used to carry current;
&ns: The +o6e+ent or o. o, eectricity aon- a .ire is si+iar to the o. o, .ater aon- a pipe #ater .i o. ,ro+ one en* o, the pipe to the other .hen the t.o en*s ha6e a *iDerence in e6e or hei-ht In a si+iar .ay5 eectricity .i o. aon- a .ire .hen the t.o en*s ha6e an eectrica *iDerence in e6e ie5 potentia *iDerence There,ore5 ,or the o. o, eectric c/rrent t.o .ire ie5 i6e .ire an* ne/tra are re
&ns: 'etas are -oo* eectrica con*/ctors5 eca/se the eectric c/rrent can pass thro/-h +etas 6ery easiy or ea+pe5 copper5 si6er5 -o*5 a/+in/+ etc On the
G3 CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& other han* pastic5 *ry .oo*5 r/er etc are -oo* eectrica ins/ators5 eca/se they *o not ao. eectric c/rrent to pass thro/-h the+ The -oo* eectrica con*/ctors are aso cae* -oo* heat con*/ctors5 eca/se the heat can pass thro/-h the+ easiy #hie the heat cannot pass thro/-h -oo* ins/ators5 so they are aso ;no.n as -oo* heat ins/ators - #tate ho5 the resistance of a 5ire 5ould change, i %f its length is increased. ii %f its diameter is decreased.
&ns: #e ;no. that the resistance o, a con*/ctor is -i6en y5 α
R
L8& 9999999999999999
(1)
In e< (1)5 & area o, cross9 section o, .ire \r]
A=π r
2
\(*82)]
ra*i/s
ia+eter82 ^ r*82
i ii
πd
&
]8= 9999999999999 (2)
/ttin- e< (2) in e< (1)5 .e -et5 πd α α πd ¿ R L8 ]8=) = L 8 ] α πd R = L8 ] 9999999999999999999 (3)
!< (3) sho.s that i, the en-th >L’ o, the .ire increases5 then its resistance .i aso increase !< (3) aso sho.s that the resistance >R’ o, the con*/ctor is in6ersey proportiona to the *ia+eter o, the .ire So i, the *ia+eter o, the .ire *ecrease* then its resistance .i increase
To reduce the brightness of a light bulb an au!iliary resistance be connected in series 5ith it or in parallel; 4hy;
&ns: In or*er to re*/ce the ri-htness o, a i-ht /5 the a/iiary resistance sho/* e connecte* in series It is eca/se5 1 In series co+ination5 the e
1 ' number of light bulbs are to be connected to single po5er outlet. 4ill they pro3ide more illumination if connected in series or in parallel; 4hy;
&ns: The /s sho/* e connecte* in parae ,or -ettin- +ore i/+ination It is eca/se5 1 In parae co+ination the potentia *iDerence across each / is the sa+e ie5 the potentia *iDerence re+ains /n*i6i*e* 2 The eO’ any /s5 there is no eDect on the ri-htness o, the other /s = 4hat is meant by the statement that an electric kettle has po5er of * > 5att;
G= CH&T!R NO 1= NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& &ns: i, an eectric ;ette is +ar;e* as 2 F .att Then it +eans that its po.er is 2000 .att #hen an operatin- 6ota-e o, 2=0 6ots is appie* across its heatin- ee+ent then it .i con6ert eectrica ener-y into heat ener-y at the rate o, 2000 J8sec (1 .att 1Jo/e8see) G 4hen an incandescent lamps burn out they usually do so Hust after they are s5itched on. 4hy;
&ns: In incan*escent a+ps the i-ht is a+en* (-eneray t/n-sten) In these a+ps ony a s+a percenta-e o, eectrica ener-y s/ppie* is con6erte* into i-ht The +aJor part o, eectrica ener-y is con6erte* into ther+a ener-y that is .hy they +ay /rn o/t .hen s.itche* on @ 4hy is it possible for a bird to perch on a high 3oltage 5ire 5ithout being electrocuted;
&ns: it is possie ,or a ir* to perch on a hi-h 6ota-e .ire .itho/t eineectroc/te* It is eca/se the .hoe o*y o, the ir* sittin- on a hi-h 6ota-e are .ire* */e to ?ero potentia *iDerent no c/rrent passes thro/-h the o*y o, the ir* there,ore the ir* is not eectroc/te* B 4hy is it dangerous to turn on a light 5hen you are in the bath tub;
&ns: The h/+an o*y is a -oo* con*/ctor o, eectricity ie hea6y c/rrent +ay pass thro/-h his8her o*y .hen to/ches a i6e .ire There,ore .hen a person in a ath t/ tries to t/rn on the s.itch o, a / he +ay -et an eectric shoc; Th/s ,or sa,ety +eas/re he sho/* not *o so
G CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
2<'"TE& (O: $1
E6E2T&OM'I(ET%#M
$: 4hat 5ays are electric and magnetic Aelds similar; %n 5hat 5ays are they di7erent; 'ns: #imilarity of electric and magnetic Aeld:
I II III I7
Both the e*s are represente* y ines o, ,orce In oth the e*s ines o, ,orce sho. the *irection ie oth the e* are 6ector e* In oth e*s the ines o, ,orce sho.s the +a-nit/*e (stren-th) o, the e* The chan-in- o, one e* -enerates the other e* 0i7erences of electric and magnetic Aeld:
I II III
Stren-th o, eectric e* is +eas/re* in a+pere .hie stren-th o, +a-netic e* is +eas/re* in -a/ss (") or tesa &n eectric e* +ay *o .or; on char-e partice .hie a +a-netic e* *oes not .or; !ectric e* ines are -enerate* on positi6e char-es an* ter+inate on ne-ati6e char-e .hie +a-netic e* ines in case o, a +a-net5 are -enerate* at North oe an* ter+inate on So/th oe
*. ' 5ire carrying a current is placed in a magnetic Aeld K. +a under 5hat circumstances, if any, 5ill the force on the 5ire be Lero; +b 9nder 5hat circumstances 5ill the force on the 5ire be ma!imum;
&ns: (a) i, a .ire carryin- c/rrent is pace* to the +a-netic e* B the ,orce on the .ire is ?ero It +eans θ = 0
= " = " = "
( I ' sin θ ( I ' sin 0 0
) I, a .ire carryin- c/rrent is pace* perpen*ic/ar to the +a-netic e* B5 then the ,orce on the .ire is +ai+/+ It +eans θ = 50 " "
= =
" ma.
( I ' sin θ ( I ' sin 50
=
( I '
-. 4hat 5ould happen if the primary 5inding of transformer 5ere connected to a battery;
&ns: Trans,or+er is a *e6ice in .hich aternatin- e+, in pri+ary coi in*/ces an aternatin- e+, in the secon*ary coi I, t.o pri+ary .in*in- o, a trans,er is connecte* to a attery nothin- .o/* happen eca/se attery is a so/rce .hich pro6i*es ony *irect c/rrent an*
GE CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
*irect c/rrent cannot pro*/ce any char-e in pri+ary coi &s a res/t no in*/ce* e+, pro*/ces in the secon*ary coi
. 4hat are the similarities bet5een motor and generator; 4hat are the di7erences; 'ns: #imilarities:
1 Both are consist o, cois 2 In oth caron r/shes are /se* 3 Both ha6e +a-netic poes
0i7erences:
1 & +otor con6erts eectric ener-y into +echanica ener-y .hie a -enerator con6erts +echanica ener-y into eectrica ener-y 2 'otor is ase* on the principa that c/rrent carryin- coi in a +a-netic e* is acte* /pon y a tor
$ E!plain the left?hand rule to determine the direction of force on a current carrying 5ire placed in a magnetic Aeld.
&ns: The +a-netic ,orce on a c/rrent carryin- .ire can e *e+onstrate* y the ,oo.in- eperi+ent ass a strai-ht .ire thro/-h +a-netic e* et.een the poes o, a P9 shape* +a-net The en*s o, the .ire are connecte* thro/-h a s.itch to the ter+ina o, a attery $o/ can oser6e that y t/rnin- on the s.itch5 the c/rrent carryin- .ire is i++e*iatey p/she* to a si*e Increasin- the c/rrent in the .ire increases the p/sh Re6erse the c/rrent in the .ire5 the *irection o, the p/sh in aso re6erse* Re6erse the *irection o, the +a-netic e* y echan-in- the positions o, the N an* s9 poe5 the +a-netic ,orce on the .ire is re6erse* On the asis o, this eperi+ent5 'ichae ,ara*ay *isco6ere* that .hen a .ire an* a +a-netic e* are at ri-ht an-e5 a ,orce acts on the .ire */e to the interaction o, the e*s The ,orce is proportiona to three ,actors4 I II III
The +a-netic e* @BA The c/rrent @IA in the .ire The en-th o, the .ire @LA
The ,orce actin- on .ire is proportiona to the pro*/ct o, L5 L an* BILB The *irection o, the ,orce actin- on .ire can e *eter+ine* y e+in-’s e,t han* r/e &ccor*in- to this r/e5 stretch the th/+5 ,oren-er5 an* the +i**e n-er o, the e,t han* +/t/ay at ri-ht an-es to each other I, the ,oren-er points in the *irection o, the +a-netic e*5 the +i**e n-er in the *irection o, the
GG CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
c/rrent5 then the th/+ .o/* in*icate the *irection o, the ,orce actin- on the .ire
*. E!plain ho5 a 5ire and a strong magnet generate an electric current.
&ns: !ectricity can e -enerate* y chan-in- +a-netic e*s in a coi o, eectricay con*/ctin- .ire 'ateria /se* ,or this p/rpose is stron- +a-netic5 coi o, eectrica .ire .rappe* aro/n* a t/e a++eter to +eas/re eectric c/rrent Ta;e a stron+a-net an* t it insi*e the .ire coi t/e Si*e the +a-net thro/-h the .ire coi5 in one *irection an* /se an a++eter to oser6e the stren-th an* si-n (positi6e or ne-ati6e) o, eectrica c/rrent pro*/ce* 'o6in- a +a-net thro/-h a coi o, .ire9or +o6in- a coi o, .ire y a +a-net9in*/ces eectrica c/rrent in the .ire The *irection that the c/rrent o.s thro/-h the .ire *epen*s on the reati6e *irection o, +otion et.een the +a-net an* the .ire coi The stren-th o, the eectrica c/rrent *epen*s on: 1) The stren-th o, the +a-net5 2) The n/+er o, .raps o, .ire in the coi5 an* 3) Ho.
&ns: C +otor: C +otor is a *e6ice5 .hich con6erts eectrica ener-y into +echanica ener-y "rincipal: the principa o, an eectric +otor is that a c/rrent carryin- coi in
a +a-netic e* is acte* /pon y a tor
t/rns .o/n* on an iron core The ar+at/re can rotate ao/t an ais perpen*ic/ar to the +a-netic e* o, an eectro+a-net The ter+inas o, the coi are connecte* to spit rin- (co++/tator) R Br/shes 5 ’ s/ppy c/rrent ,ro+ the attery co++/tator re6erses the s/ppie* c/rrent e6ery ha, rotation
G CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
4orking: #hen c/rrent I is passe* in the ar+at/re cois the+ the coi is
acte* /pon y a tor
.ashin- +achines5 ra*ar5 co++/nication *e6ices5 teephone5 tee6ision etc
E!plain the phenomenon of mutual induction.
&ns: Mutual induction: The pheno+enon5 in .hich c/rrent is in*/ce* in a circ/it */e to a chan-e o, c/rrent in another circ/it5 is ;no.n as +/t/a in*/ction OR The pheno+enon in .hich in*/ce* e+, is pro*/ce* in the secon*ary coi .hen c/rrent is chan-in- the pri+ary coi is ;no.n as +/t/a in*/ction E!planation: In the -i6en -/re are t.o cois pace* near each other The
coi & is pace* in attery circ/it an* is cae* pri+ary coi The coi B is connecte* .ith -a6ano+eter an* is cae* the secon*ary coi &ccor*in- to the principe o, eectro+a-netic in*/ction a chan-in- c/rrent in one coi can pro*/ce* an in*/ce* e+, in a nei-horin- coi So startin-5 stoppin- or 6aryin- c/rrent in a pri+ary coi a .i pro*/ce* e+, in coi B The c/rrent in coi B asts ony as on- as c/rrent in the coi & is chan-in-
1. #ketch and describe an '.2 generator.
&ns: '.2 Ienerator: &C -enerator is a *e6ice5 .hich con6erts +echanica ener-y into eectrica ener-y
GK CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& "rinciple: The principe o, &C -enerator is ase* on eectro+a-netic
in*/ction &n in*/ce* e+, is pro*/ce y chan-in- +a-netic / thro/-h the coi 2onstruction: & -enerator consists o, a rectan-/ar coi o, N t/rns .o/n*
on an iron core The asse+y o, coi p/s cyin*er is cae* ar+at/re It can rotate ao/t an ais OO’ perpen*ic/ar to a /ni,or+ +a-netic e* o, / intensity >B’ Rin- R5R’ are connecte* to the ter+inas o, coi Br/shes ’ si*e aon- the rin-s an* connect the coi to the eterna circ/it
4orking: S/ppose in the e-innin- the coi is 6ertica .ith its si*e & /p.ar*
an* si*e B *o.n.ar* The si*es & an* B are +o6in- parae to the e*5 so rate o, chan-e o, / thro/-h the coi is ?ero an* in*/ce* e+, is ?ero as .e &,ter co+petin- one ri-ht an-e to the e* an* rate o, chan-e o, / is +ai+/+ In this .ay the rotation o, the coi in a +a-netic e* -enerator an aternatin- in*/ce* e+, 9ses: &C -enerators are instae* at Tarea5 'an-a an* #arsa; etc an* are
/se* to con6ert the ;inetic ener-y o, .ater ,as into eectrica ener-y In petro an* *iese operate* &C -enerators5 the che+ica ener-y is con6erte* into eectrica ener-y = 4rite note on transformer.
&ns: Transformer: &C trans,or+er is a +/t/a in*/ctance eectrica *e6ice .hich steps /p or steps *o.n &c 6ota-e "rinciple: & trans,or+er operates on the principe o, +/t/a in*/ction &
chan-in- c/rrent in a pri+ary coi can ca/se an in*/ce* e+, an* in*/ce* c/rrent in a nei-horin- secon*ary coi 2onstruction: & typica Etrans,or+er has an iron core on .hich t.o cois are
.o/n*5 pri+ary coi .ith Np t/rns an* secon*ary .ith Ns t/rns The pri+ary coi is connecte* to &C 6ota-e 7p an* o/tp/t 7s is otaine* across the secon*ary cois ter+inas
0 CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
4orking: The &C in the pri+ary coi pro*/ces a chan-in- +a-netic / in
the iron core The chan-in- / thro/-h the secon*ary coi -i6e rise to an in*/ce* e+, 7s in the secon*ary coi The 6ota-e an* n/+er o, t/rns in pri+ary an* secon*ary cois are reate* y e
1 & trans,or+er that raises the inp/t 6ota-e 7 p to a hi-her 6ota-e 7 s has Ns^Np an* is cae* a step /p trans,or+er 2 & trans,or+er that *ecreases the inp/t 6ota-e 7p to a o.er 6ota-e 7s has Np^Ns an* is cae* a step *o.n trans,or+er 9ses:
1 or char-in- 6ota-e in &C circ/it 2 In the *esi-ns o, circ/its ,or co++/n/nication5 in ra*io5 tee6ision5 teephone5 ra*ar etc 3 In trans+ission an* *istri/tion o, eectrica po.er ,ro+ the *istant -eneratin- pant to in*/stria an* ho/seho* /sers
G 4hat are magnetic e7ects of a steady current;
&ns: ,oo.in- the +a-netic eDects o, a stea*y c/rrent I
ield due to a straight 5ire: To in6esti-ate the +a-netic e* ao/t
a c/rrent carryin- .ire5 pace a .ire 6erticay thro/-h a piece o, car* oar* ass an eectric c/rrent thro/-h the .ire Sprin;e iron in-s on the car*oar* aro/n* the .ire Tap the car* oar* /nti the in-s arran-e the+se6es in concentric circes The circ/ar ines in*icate that the ine o, ,orce ,or+ cose* oops The intensity o, the +a-netic e* ao/t the .ire aries *irecty as the +a-nit/*e o, the c/rrent o.in- in the .ire The +a-netic e* o, this c/rrent can aso e trace* y +eans o, a +a-netic co+pass To n* the *irection o, the +a-netic e* ao/t the .ire5 /se the ri-ht han* r/e The r/e states that i, @the c/rrent carryin- .ire is -raspe* y the ri-ht han* .ith the th/+ in the *irection o, the c/rrent4 the n-ers encirce the .ire in the *irection o, the e*A
1 CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
II
The magnetic Aeld around a coil: The stren-th o, the +a-netic e*
step /p y a piece o, .ire carryin- a c/rrent can e enhance* at a specic ocation it the .ire is ,or+e* into a oop The +a-netic e* insi*e the oop is create* y the c/rrent o.in- tho/-ht the .ire The +a-netic e* r/ns in the sa+e *irection a aro/n* the oop &ppy the ri-ht han* r/e aro/n* the oop The n-ers a.ays point in the sa+e *irection insi*e an* o/tsi*e the oop Notice in (-) that the +a-netic e* ines enter at the e,t si*e o, the c/rrent oop an* eit at the ri-ht Th/s5 one si*e o, the oop acts as thro/-h it .ere the north poe o, +a-net an* the other act as a so/th poe The ,act that the e* set/p y s/ch a c/rrent oop ears a stri;in- rese+ance to the e* o, a ar +a-net
III
The magnetic Aeld due a solenoid: I, a on-5 strai-ht .ire is
.rappe* into a coi o, se6era cosey space* oops5 the res/tin*e6ice is a soenoi* or5 as it is o,ten cae*5 an eectro+a-net This *e6ice is i+portant is +any appication since it acts i;e a +a-net ony .hen it carries a c/rrent The +a-netic e* insi*e a soenoi* increases .ith the c/rrent an* is proportiona to the n/+er o, cois per /nit en-th Note that the e* ines insi*e the soenoi* are +erey parae5 /ni,or+y5 space* an* cose to-ether This in*icates that the e* insi*e the soenoi* is /ni,or+ an* stron- The eterior e* at the si*es o, the soenoi* is non /ni,or+ an* is +/ch .ea;er than the e* insi*e The e* ines enter at one en* o, the soenoi* an* e+er-e at the other This +eans that one en* o, the soenoi* acts as tho/-h it .ere the north poe o, a +a-net .hies the other an* acts as tho/-h it .ere the So/th poe -(a) The poarity o, a c/rrent carryin- soenoi* can e *eter+ine* y the ,oo.in- r/e Ho* the soenoi* in yo/r ri-ht han*
2 CH&T!R NO 1 NORTH NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
y c/rin- the n-ers in the *irection o, the c/rrent4 the stretche* th/+ .o/* in*icate to.ar*s the North oe i-() i-()
@ E!plain torue on a current carrying coil in a magnetic Aeld.
&ns: Tor
B 4rite a note on mo3ing coil loud speaker.
&ns: 'ost Lo/*spea;ers are o, the +o6in- coi type5 .hich /ses the ,act that a c/rrent carryin- con*/ctor eperiences a ,orce .hen in a +a-netic e* & o/* spea;er consists o, a per+anent +a-net .ith a centra cyin*rica poe an* a s/rro/n*in- rin- poe .hich creates a stron- +a-netic e* in the -ap et.een the poes5 a short cyin*rica coi .hich can +o6e ac;.ar* an*
3 CH&T!R NO 1 NORTH NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
,or.ar* thro/-h a short *istance in the +a-netic e* an* .hose t/rns are at ri-ht an-es to the e*4 an* a paper cone attache* to the coi #hen aternatin- c/rrent ,ro+ say5 a ra*io or a recor* payer passes thro/-h the coi it is ,orce* to +o6e in or o/t *epen*in- on the c/rrent *irection accor*in- to e+in-sA e,t han* r/e The paper cone +o6es .ith the coi an* th/s sets /p so/n* .a6es in the s/rro/n*in- air o, the sa+e ,re
$J 4rite note on electromagnetism.
&ns: &ns: The The +a +a-n -net etis is+ + pro* pro*/c /ce* e* */e */e to the the o. o. o, c/r c/rrent rent is ;no. ;no.n n as eectr eectro+a o+a-net -netis+ is+ This This sho.s sho.s that that +a-neti +a-netic c eDect eDect can e pro*/c pro*/ce* e* y eectric eDect This .as rst o, a pro6e* y a /tch scientist Oerste* in 120 He *isco6ere* that .hen c/rrent passes thro/-h the con*/ctor then esi*es eectric e* it can aso pro*/ce a +a-netic e* .here as a +o6inchar-e pro*/ces oth eectric an* +a-netic e* O/ste* eperi+ent can e practicay *e+onstrate* as Ta;e a on- c/rrent carr carryi yinn- .ir .ire an* an* pass pass it thro thro//-h h a car car* oar oar* * Both Both o, the the .ir .ires are are attache* to the ter+inas o, the attery So+e iron in-s are sprin;e* o6er the car* oar* #hen the c/rrent is ao.e* to pass thro/-h the .ire5 then the iron in-s .i e attracte* y the .ire #hich sho.s that +a-netic e* is pro*/ce* aro/n* the .ire
= CH&T!R NO 1E NORTH NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
2<'"TE& (O $=
%(T&O092TO&D %(T&O092T O&D E6E2T&O(%2# E6E2T&O(%2 #
Electronics:
The ranch o, appie* physics .hich *eas .ith the *e6eop+ent o, eectron e+ittin- *e6ices an* their /tii?ation is cae* eectronics . 4hat do you mean by analogue;
&ns: !ectronics can e cassie* into t.o +ain ranches: anao-/e eectronics an* *i-ita eectronics In practica appication5 a co+ination o, oth ranches is o,ten /tii?e* Those
&ns: 2athode?ray Oscilloscope: Catho*e9ray t/es ha6e eco+e part o, e6ery*ay i,e They can e ,o/n* in the screens o, tee6ision sets an* co+p/ter +onitors In the physics aoratory5 .e /se the catho*e9ray t/e in the oscioscope to st/*y .a6e,or+s The catho*e9ray oscioscope (CRO) (CRO) consists consists o, the ,oo.in- co+ponents: i ii iii i.
ii.
iii.
The eectron -/n The *eectin- pates & /orescent screen The electron gun: It consists o, a -ri*5 .hich is connecte* to a ne-ati6e potentia The +ore ne-ati6e is the potentia5 the +ore eectrons .i reach the ano*e an* the screen The n/+er o, eectrons reachin- the screen *eter+ines the ri-htness o, the i-ht Hence5 the ne-ati6e potentia o, the -ri* can e /se* as a ri-htness contro The other ,eat/re in the eectron -/n is the /se o, the ano*e The ano*e at positi6e potentia acceerates the eectrons an* the eectrons are ,oc/se* into ne ea+ as they pass thro/-h the ano*e The de8ecting de8ect ing plates: plat es:
T.o T.o pairs o, pates are tte* tte* in CRO CRO 7ota-es 7ota-es can e appie* to these pates so as to *eect the eectron ea+ The $ $9pates 9pates .i ca/se *eection in the 6ertica *irection .hen a 6ota-e is appie* across the+ On the other han*5 the _9pates .i ca/se the eectron ea+ to e *eecte* in the hori?onta *irection i, a 6ota-e is appie* across the+ The 8uorescent sc screen: The screen is coate* .ith a /orescent sat5 ,or ea+pe5 ?inc s/phi*e #hen the eectrons hit the screen5 it .i ca/se the sat to pro*/ce a ash o, i-ht an* hence a ri-ht spot on the screen
oscioscope (CRO) is /se* to see the .a6e,or+ .a6e,or+ o, a repetiti6e repetiti6e 9ses: & catho*e ray oscioscope eectron si-na The si-na is a+pie* or atten/ate* as re
CH&T!R NO 1E NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
*. 4hat are logic gates; 0ra5 symbol and truth table of the follo5ing logic gated. +a'(0 gate +bO& gate +c (OT gate +d('(0 gate +e(O& gate 'ns: 6ogic gates: The eectrica circ/its That er,or+ one or +ore o-ica
operations on one or +ore inp/t si-nas are cae* o-ic -ates recio/s artices5 cash an* i+potent *oc/+ents etc are ;ept in sa,es The *oor o, a sa,e is opene* an* cose* y a certain or*er o, a set o, s.itches & syste+atic or*ere* syste+ is cae* a o-ic -ate I, the /ttons o, s.itches are presse* in ri-ht or*er5 the *oor o, the sa,e .i open Ho.e6er5 i, the /ttons are presse* in .ronor*er5 the aar+ e-ins to rin- +' '(0 gate:
The &N -ate has t.o inp/ts s.itches & an* B The / Y .i i-ht i, oth the s.itches are cose* This .i ao. c/rrent to o. thro/-h the /5 i/+inatin- the a+ent The &N -ate is an eectronic circ/it that -i6es a hi-h o/tp/t (1)5 ony i, a its inp/ts are hi-h & *ot () is /se* to sho. the &N operation
+K O& gate:
The OR -ate consists o, t.o inp/t s.itches & an* B the / Y .i e i-ht i, either & or B is s.itch cose* This ao.s the c/rrent to o. thro/-h the /5 i/+inatin- the a+ent .hen either o, the s.itches is cose* The OR -ate is an eectronic circ/it that -i6es a hi-h o/tp/t (1) i, one or +ore o, its inp/ts are hi-h & p/s ([) is /se* to sho. the OR operation
+2 (OT gate:
The NOT -ate is an eectronic circ/it that pro*/ces an in6erte* 6ersion o, the inp/t at its o/tp/t It is ;no.n as in6erter I, inp/t 6ariae is &5 then the in6erte* o/tp/t is ;no.n as NOT & this is sho.n as tr/th tae are -i6en in the -/re
A
Its sy+os an*
+0 ('(0 gate:
This is a NOT9&N -ate .hich is e
E CH&T!R NO 1E NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& hi-h i, any o, the inp/ts are o. The sy+o is an &N -ate .ith a s+a circe on the o/tp/t The s+a circe represents in6ersion
+E (O& gate:
This is a NOT9OR -ate .hich is e
-. E!plain the di7erence bet5een analogue and digit al electronics. 'ns: 'nalogue electronics:
The ranch o, eectronics consistin- o, s/ch circ/its5 .hich processes anao-/e
The ranch o, eectronics5 .hich pro6i*es the *ata in the ,or+ o, a +ai+/+ an* +ini+/+ 6ota-e si-nas5 is ;no.n as *i-ita eectronics In this type o, *ata5 the chan-es are not contin/o/s In ,act5 one part o, the *ata
the +ateria as a .hie #e can these eectrons as ,ree eectrons eca/se they can +o6e ,reey thro/-h the +eta &n eectron tra6ein- o/t.ar*s on the s/r,ace cannot escape as it is he* ac; y the attracti6e ,orces o, the ato+ic n/cei #hen a +eta is heate*5 ho.e6er5 so+e o, the eectrons +ay -ain eno/-h ener-y to escape ,ro+ the s/r,ace o, the +eta This eDect is ;no.n as ther+ionic e+ission Ther+ionic e+ission can e pro*/ce* y eectricity heatin- a ne t/n-sten a+ent 1. 4rite a note on electron gun.
consists o, a -ass t/e at a 6ery o. press/re The eectrons are pro*/ce* y ther+ionic e+ission ,ro+ a t/n-sten a+ent heate* y a E6 s/ppy & hi-h positi6e potentia (se6era tho/san* 6ots) is connecte* to a cyin*rica ano*e ([) The eectron .i e acceerate* to the ano*e in a ne ea+ o, eectrons This eectron ea+ is cae* as catho*e rays as they are pro*/ce* ,ro+ the catho*e or ne-ati6e eectro*e (9) The path o, these ,ree eectrons can e aDecte* y eectric an* +a-netic e* +a 0e8ection by electric Aeld:
G CH&T!R NO 1E NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& &n eectric e* can e set /p y appyin- a potentia *iDerence across t.o parae +etas pace* hori?ontay some *istance apart #hen an eectron ea+ passes et.een the t.o pates5 it can e oser6e* The reason einthat eectrons are attracte* y the positi6e pate an* repee* y the ne-ati6e pate +b 0efection by magnetic Aeld:
& +a-netic e* is appie* at ri-ht an-es to the ea+ o, eectrons y ha6int.o poes o, the ea+ o, eectrons y ha6in- t.o poes o, the +a-net pace* as sho.n is -: it can e oser6e* that the eectrons ea+ is *eecte* y +a-netic e* Since eectrons are ne-ati6e5 the ea+ o, eectrons .o/* e e
=: 5hat are the uses of logic gates; 'ns:. Lo-ic -ates are in ,act the /i*in- oc; o, *i-ita eectronics !6ery *i-ita
pro*/ct5 i;e co+p/ter5 +oie5 cac/ators e6en *i-ita .atches5 contains o-ic -ates5 o-ic -ates are aso /se* to per,or+ *iDerent types o, hos in *i-ita eectronics ie ho/se sa,ety aar+ etc 4ireless door and 5indo5 alarm:
To pre6ent that yo/r chi* *o not .a;e* o/tsi*e the ,ront *oor .itho/t tein- yo/5 a specia type .ireess aar+ can pre6ent s/ch a ris; an* ;eep yo/r chi* sa,ety insi*e #hen the *oor is opene* the aar+ e+its a contin/o/s 120B so/n* (/nti the *oor is sh/t) to te yo/ that yo/r chi* is at ris; o, ea6in- Th/s *i-ita eectronic has ,aciitate* /s in a respect o, o/r *aiy i,e
CH&T!R NO 1E NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
K CH&T!R NO 1G NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& 2<'"TE& (O $G TE2<(O6OID
%(O&M'T%O( '(0 2OMM9(%2'T%O(
%nformation technology:
The scientic +etho* o, storin-5 protectin-5 processin-5 trans+ittin-5 recei6in- an* retrie6in- in,or+ation is cae* in,or+ation technoo-y Telecommunication:
The +etho* that is /se* to co++/nicate in,or+ations to ,ar oD paces instanty is cae* teeco++/nication Teephone5 ra*io5 T75 ,a5 tee +achine an* +achine are a ,e. o, conte+porary *e6ices /se* ,or teeco++/nication $. 0eAne %.T. 'ns: %nformation technology:
The scientic +etho* o, storin-5 protectin-5 processin-5 trans+ittin-5 recei6in- an* retrie6in- in,or+ation is cae* in,or+ation technoo-y 'o*ern science an* technoo-y are 6ery rapi*y *isco6erin- an* in6entin- ne. techni
&ns: In the co+p/ter5 cac/ation an* instr/ction are inserte* y an inp/t /nit Ps/ay a ;ey roa*5 si+iar to a type .riter is /se* ,or this p/rpose The *iDerent ,/nctions o, the ;eyoar* are aso controe* y a specia instr/+ent cae* a +o/se There are se6era other +etho*s to ,ee* in,or+ation into the co+p/ter5 .hich inc/*es oppy *is;s an* C’s Inp/t *e6ices sen* the recei6e* *ata to CP so that its arran-e+ent an* anaysis +ay e *one -. 4hat do you mean by graphic designing;
&ns: The process to *ra. a re
&ns: &T' stan* ,or a/to+ate* teer +achine or a/to+atic teer +achine &n &T' ,or *eposits5 .ith*ra.as5 acco/nt in,or+ation an* other types o, transaction o,ten thro/-h interan; net.or;s 1. #%M stands for 5hat;
&ns: SI' stan*s ,or s/scrier i*entication +o*/e They are /se* in +oie sets SI' is /se* ,or ta;in- to other peope It can aso store n/+er in its +e+ory
K0 CH&T!R NO 1G NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
.$. 4hat is a computer; 4rite the parts of computer. 2omputer:
Co+p/ter is an eectronic +achine .hich a,ter anay?in- an* arran-in- the -i6en in,or+ation5 presents it in a 6ery short ti+e & the .or; is *one y the co+p/ter in the i-ht o, those instr/ctions .hich cae* @pro-ra+A an* is sa6e* in its +e+ory Co+p/ter preser6es this pro-ra+ an* in,or+ation in its +e+ory so on- as .e *esire "arts of computer:
The i+portant parts o, a co+p/ter are -i6en eo.: $. %nput de3ices:
In the co+p/ter5 cac/ations an* instr/ctions are inserte* y an inp/t /nit Ps/ay a ;eyoar*5 si+iar to a type .riter is /se* ,or this p/rpose The *iDerent ,/nctions o, the ;eyoar* are aso controe* y a specia instr/+ent cae* a @+o/seA There are se6era other +etho*s to ,ee* in,or+ation into the co+p/ter5 .hich inc/*es oppy *iscs an* Cs Inp/t *e6ices sen* the recei6e* *ata to CP so that its arran-e+ent an* anaysis +ay e *one *. 2entral processing unit:
It is a type o, a rain o, the co+p/ter .hich per,or+s the .hoe Jo This part co+prises o, a contro /nit an* +e+ory /nit -. Output de3ice:
The interna .or;in- o, the co+p/ter is represente* y the o/tp/t /nit It rese+es a tee6ision set .hich is cae* a +onitor & the processes can e oser6e* on its screen .hie the print o/t o, the res/t can e ta;en on a paper .ith the hep o, an attache* printer 'oreo6er o/tp/t can e recor*e* on a oppy *isc or C’s ast .or;in- o, the co+p/ter5 acc/rate so/tion o, the -i6en in,or+ation5 ar-e +e+ory an* capaiity o, *eri6in- res/ts is increasin- its i+portance *ay y *ay an* perhaps5 there is no *epart+ent e,t .here +an is not enetin- its /ses . 4rite the importance of %.T 'ns: %nformation Technology %mportant in Kusiness:
There are +any /sinesses .hich are in nee* o, the so,t.are pac;a-es ,or satis,yin- their operationa as .e as ,/nctiona nee*s or ,/in- this re
K1 CH&T!R NO 1G NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& /e to the *e6eop+ent o, the in,or+ation technoo-y sector5 the co+panies are ein- ae to ;eep the+se6es a.are o, the chan-es in the -oa +ar;ets It pays an i+portant roe in easiy so6in- the +athe+atica proe+s an* in the proJect +ana-e+ent syste+ It has a -reat /se in the a/to+ate* pro*/ction o, sensiti6e in,or+ation5 a/to+ate* /p9-ra*ation o, the i+portant /siness processes an* the a/to+ate* strea+inin- o, the 6ario/s /siness processes It has aso paye* an i+portant roe in the areas o, co++/nication an* a/to+ate* a*+inistration o, entire syste+s %mportance of information technology in education:
I+portance o, in,or+ation technoo-y in e*/cationa sector is .e9;no.n It heps the st/*ents as .e as the teachers in st/*yin- the co/rse +ateria easiy eca/se o, ,ast access St/*yin- the s/Jects .ith the hep o, onine iraries an* *ictionaries has +a*e -raspin- an* increasin- the ;no.e*-e easy ,or he st/*ents The inc/sion o, in,or+ation technoo-y in the sya/s in schoos5 coe-es an* /ni6ersities has hepe* the+ in -raspin- the s/Ject .e an* -ettin- their asics ceare* Since5 +any e*/cationa centers ha6e the onine -ra*in- syste+4 it has een a oon ,or the parents o, the chi*ren to ;eep a ta on their per,or+ance arents can aso -et the *etais o, the atten*ance recor* o, their chi* in schoos .1 4hat is the importance of e?mail and internet;
&ns: By /sin- internet5 no. .e can co++/nicates in a ,raction o, secon*s .ith a person .ho is sittin- in the other part o, the .or* To*ay ,or etter co++/nication5 .e can a6ai the ,aciities o, e9+ai 1 %nformation: The i--est a*6anta-e that internet oDerin- is in,or+ation The internet an* the .or* .i*e .e has +a*e i, easy ,or anyone to access in,or+ation5 an* it can e o, any type5 as the internet is oo*e* .ith in,or+ation 2 Kusiness: #or* tra*e has seen a i- oo+ .ith the hep o, internet5 as it has eco+es easier ,or /yers an* seers to co++/nicate an* aso to a*6ertise their sites 3 #ocial (et5orking: To*ay socia net.or;in- sites ha6e eco+e an i+portant part o, the onine co++/nity &+ost a /sers are +e+ers an* can /se i, ,or persona an* /siness p/rposes = Entertainment: On internet .e can n* a ,or+s o, entertain+ent ,ro+ .atchin- +s to payin- -a+es onine a+ost anyone can n* the ri-ht ;in* o, entertain+ent ,or the+se6es E?2ommerce: Is the concept /se* ,or any type o, co++ercia +ane/6erinor /siness *eas that in6o6es the trans,er o, in,or+ation across the -oe 6ia internet E #hopping: It has eco+e a pheno+enon associate* .ith any ;in* o, shoppin-5 a+ost anythin- It has -ot a rea a+a?in- an* ran-e o, pro*/cts ,or+ ho/seho* nee* to entertain+ent G #er3ices: 'any ser6ices are no. pro6i*e* on the internet s/ch as onine an;in-5 Jo see;in-5 p/rchasin- tic;ets ,or yo/r ,a6orite +o6ies5 an* -/i*ance ser6ices on array o, topic in the e6er aspect o, i,e5 an* hote reser6ations an* is payin- .*
;eyoar*5 a *ispay screen5 an* a po.er,/ circ/it oar* .ith +icroprocessors that +a;e each phone a +iniat/re co+p/ter #hen connecte* to a .ireess net.or;5 this /n*e o, technoo-ies ao.s yo/ to +a;e phone cas or echan-e *ata .ith other phones an* co+p/ters aro/n* the .or* The co+ponents operate so ecienty that a i-ht .ei-ht attery can po.er yo/r phone ,or *ays
K2 CH&T!R NO 1G NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& To*ay5 ce phones t in the pa+ o, yo/r han*5 .ei-h ony a ,e. o/nces5 an* oDer ,eat/res s/ch as coor -raphic5 +/sica rin- tones an* 6oice9acti6ate* *iain- Ony a ,e. years a-o5 the eectronic in this see; *e6ice .o/* h a6e e* a ar-e rie,case & ce phone is reay 6ersatie ra*io '/ch i;e a .a;ie ta;ie5 a ce phone recei6es an* sen*s ra*io si-nas Beca/se these ra*ios connect into a net.or;5 ce phones oDers +/ch +ore5 the aiity to ca any teephone any.here in the .or*5 internet access an* *ata ser6ices - :
echan-in- the physica 6ersions o, the *oc/+ent The in,or+ation is instea* con6erte* to an eectronic si-na an* sent thro/-h a phone ine to the other ocation Scannin- an* e+ai capaiities are so.y repacin- ,a +achine5 /t it is sti a necessary *e6ice ,or +ost oces5 especiay in /sinesses .here *oc/+ents nee* to e si-ne* There are se6era co+ponents re
K3 CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
Chapter No: 18
RADIOACTIVITY
(uclear physics:
The ranch o, physics .hich *eas .ith the st/*y o, properties an* str/ct/re o, n/ce/s is ;no.n as n/cear physics #tructure of atom:
The ato+ consists o, t.o parts5 the centra *ense part ha6in- positi6e char-e is cae* n/ce/s5 .hich consists o, protons an* ne/trons The o/ter part consists o, circ/ar orits in .hich eectrons re6o6e aro/n* the n/ce/s There are three ,/n*a+enta partices present in an ato+ ie proton5 ne/tron an* eectron The o/ter part consists o, circ/ar re6o6es aro/n* the n/ce/s N/ce/s is spherica in shape The *ia+eter o, n/ce/s is 10 91=+ an* that o, ato+ is 10 910+ The n/+er o, protons an* ne/trons insi*e the n/ce/s are ;no.n as n/ceons The +ass o, proton is 1 ×10 −2
+ 1 × 10−15
;- an* its char-e is e
− 1 × 10−15
;- an* its char-e is C In a ne/tra ato+ the n/+ers o, eectrons are e
K= CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& cae* +ass n/+er It is represente* y @&A &n ato+ @_A can e represente* as ,
=A
%sotopes: ?
The ato+s o, an ee+ent ha6in- sa+e ato+ic n/+er /t *iDerent +ass n/+ers are cae* isotopes O&
&to+s o, the sa+e ee+ents containin- the sa+e n/+er o, protons /t *iDerent n/+er o, ne/trons in their n/cei are cae* isotopes E!planation: ?
& the ato+s o, an ee+ent contain the sa+e n/+er o, protons an* eectron /t they +ay ha6e *iDerent n/+er o, ne/trons !a+pe4 a the /rani/+ ato+s contain K2 protons an* K2 eectrons /t the n/+er o, ne/trons are *iDerent So+e /rani/+ ato+s contain 1=3 ne/trons .hie other contains 1=E ne/trons & the ato+s ha6e sa+e n/+er o, protons that’s .hy the ato+ic n/+er o, a the ato+s o, an ee+ent re+ains the sa+e B/t the +ass n/+er is *iDerent */e to presence o, *iDerent n/+er o, ne/trons 'ass n/+er o, /rani/+ ato+ containin- 1=3 ne/trons &
No o, rotons [ No o, ne/trons
&
K2
&
23
[ 1=3
'ass n/+er o, /rani/+ containin- 1=E ee+ents & No o, protons [ No o, ne/trons K2 [1=E & 23 The /rani/+ ee+ents has +ainy t.o isotopes P23
K2
P23
K2
Isotopes ha6e sa+e che+ica properties */e to presence o, sa+e n/+er o, eectrons in its 6aence she B/t *iDerent physica properties */e to presence o, *iDerent n/+er o, ne/trons &adioacti3ity: ?
The spontaneo/s an* /ncontroae *isinte-ration o, the n/ce/s o, certain hea6y ato+s .ith the e+ission o, apha5 eta an* -a++a rays8partices is cae* ra*ioacti6ity E!planation: ?
The hea6y ee+ents ha6in- ato+ic n/+er %^2 i;e /rani/+5 thori/+5 ra*i/+ etc are /nstae To -ain staiity they e+it so+e in6isie ra*iations .hich aDect the photo-raphic pate J/st i;e or*inary i-ht rays These ee+ents .hich e+it ra*iation are ;no.n as ra*ioacti6e ee+ent an* this property o, e+ittinin6isie ra*iations is ;no.n as ra*ioacti6ity This pheno+enon .as rst *isco6ere* y the rench scientist Henri Bec
K CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& 52
> 236
50
Th 234
+
2
H 4
+
E
In ao6e ea+pe /rani/+ ato+ has een con6erte* to Thori/+ ato+ ee+ent #hen a hea6ier ato+ *isinte-rates its se, it is ;no.n as nat/ra ra*ioacti6ity .hie the *isinte-ration o, articia ra*ioacti6e ee+ents is ;no.n as articia ra*ioacti6ity 9nit:
The SI /nit o, ra*ioacti6ity is ec
The acti6ity o,
& s+a
?
1 The 9rays consist o, *o/e positi6e char-e ha6in- +ass e
2 The char-e on 9rays8 partices is e
3 The spee* o, 14 ×10 m / s
?
=
?
rays *epen*s /pon the ra*ioacti6e ee+ent an* ran-es ,ro+ 16 ×10 m / s
to
9rays ioni?e the -as thro/-h .hich they pass
9rays aDect the photo-raphic pate E They pro*/ce /orescence in ?inc s/phi*e G They are aDecte* y eectric an* +a-netic e*s &t at+ospheric press/re they tra6e a s+a *istance in air =c+ to c+ Keta rays:
@
1
@
9rays carries ne-ati6e char-e The +ass an* char-e o, that o, eectrons @
2 3 =
?
The ioni?ation po.er 9rays is ess than that o, 9rays They pro*/ce /orescence in Bari/+ atinocyni*e They are aDecte* y eectric an* +a-netic e*s They can pass thro/-h thic; ayer o, +atter /p to 1c+
9rays is e
KE CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& @
E They aDect the photo-raphic pate /t the eDect pro*/ce* y
9rays is +ore
?
than 9rays G They are e+itte* y ra*ioacti6e ee+ent .ith a -reat spee* Iamma rays:
1 They +o6e .ith the spee* o, i-ht @
2 The ioni?ation pro*/ce* is 6ery s+aer as co+pare* to A
3
?
an* 9rays
9rays aDect the photo-raphic pate /t this eDect is +/ch hi-her than that @
o, A
=
9rays
9rays aso pro*/ce /orescence in Bari/+ patinocyni*e A
@
The penetratin- po.er o, 9rays is +/ch -reater than 9rays E They are not aDecte* y eectric an* +a-netic e*s ie They are ne/tra A
G
9rays are s/ch eectro+a-netic .a6es .hich are e+itte* y the n/ce/s
The ti+e inter6a in .hich ha, o, the ato+s in any -i6en sa+e *ecay into *a/-hters ee+ents is ;no.n as ha, i,e o, the parent ee+ent E!planation:
&s .e ;no. that any ra*ioacti6e ee+ent e+ittin- ra*iations is con6erte* into another ee+ent .ith the passa-e o, ti+e The ori-ina ee+ent is ;no.n as parent ee+ent .hie the ne. ee+ent ,or+e* is ;no.n as *a/-hter ee+ents #hen an ato+ e+its apha partices then the ne. ee+ent ,or+e* is -i6en y4 / A
Z
/ A−4
Z − 2
+
α
Si+iary its Beta partices are e+itte* then4 / A
Z
Z +1
/ A
+ β
ro+ ao6e reactions .e can say that the protons an* ne/trons present insi*e the n/ce/s are contin/o/sy chan-in- to one another #hen a ne/tron e+its Beta partices it is con6erte* into proton Th/s the char-e n/+er o, the *a/-hter ee+ent increases y one /nit #e cannot esti+ate the i,e o, a sin-e ato+ There,ore the ti+e inter6a in .hich ha, o, the parents *ecay into *a/-hter ee+ents is ;no.n as ha, i,e iDerent ee+ents ha6e *iDerent ha, i6es ran-in,ro+ a ,raction o, secon* to 10 years I, .e ha6e 205000 ee+ents o, a sa+pe5 then a,ter rst ha, i,e 105000 .i *ecay into *a/-hters’ ee+ents #hie in the secon* ha, i,e 000 .i re+ain as parent ee+ents %sotopes:
The ato+ o, sa+e ee+ent ha6e sa+e ato+ic n/+er /t *iDerent +ass n/+er are cae* isotopes Hy*ro-en has three isotopes ie 1H1 51H2 an* 1H3 &adioisotopes:
The isotopes o, an ee+ent .hich are /nstae an* *ecays y e+ittinapha5 Beta an* -a++a rays are ;no.n as ra*ioisotopes
KG CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& E!planation:
So+e isotopes in nat/re are stae /t so+e are /nstae They *ecay an* are ra*ioacti6e s/ch isotopes are ;no.n as ra*io isotopes 'any o, the+ are nat/ray occ/rrin- .hie so+e are pro*/ce articiay y o+ar*+ent o, s/ ato+ic partices !a+pes o, articiay prepare* ra*ioisotopes are $a 24
11
2
,o 2
&3
I 131
Einsteins Mass Energy Euation:
In 1K05 !instein -a6e his theory o, reati6ey .hich containe* the i*ea that ener-y an* +atter are interchan-eae accor*in- the !instein +ass ener-y e
#here ! is the ener-y otaine* as a res/t o, +ass V+V .hen it is -i6en the spee* o, i-ht VcV .here VcV is the spee* o, i-ht an* its 6a/e is 3 _ 10 +8sec ro+ ao6e e
The spittin- o, hea6y n/ce/s into ,ra-+ents .ith the e+ission o, ener-y .hen o+ar*e* y a ne/tron is cae* n/cear ssion E!planation:
N/cear ssion .as rst *isco6ere* y Otto Hann an* rit? Strass+an o+ar*in- /rani/+ K2P23 n/ce/s .ith so. ne/trons /e to .hich 23E co+po/n* n/ce/s K2P .ere ,or+e* an* th/s ro;e into ,ra-+ents .ith the reease o, t.o or three ne/trons an* a ar-e a+o/nt o, ener-y 5 This process is epresse* as ,oo.s 4 0
n
1
+ 52 > 23&
(a141
> 23
(a 141 +
&
Kr 52
3
+30 n1 + &
Kr 52
&
#hereas5
52
3
an*
represents the Bari/+ an* Frapton n/cei
In a ssion reaction5 the s/+ o, +asses o, the pro*/ce n/cei an* ne/trons is ess than the +ass o, the ori-ina n/ce/s Th/s the +ass *iDerence res/ts in the reease o, ener-y accor*in- to !instein’s +ass ener-y e
In a ssion process each n/ce/s e+its ao/t t.o to three ne/trons These ne/trons +ay coi*e .ith the other /rani/+ n/cei an* ca/se ssion in the+ This process contin/es5 +ore an* +ore ne/trons are e+itte* th/s a chain is ,or+e* ;no.n as ssion chain reaction I, the chain reaction is not controe*5 then a ar-e a ar-e a+o/nt o, ener-y is reease* in the ,or+ o, heat an* ;inetic ener-y o, ,ra-+ents in a 6ery short ti+e !a+pe4 eposion o, ato+ic o+ I, the ssion chain reaction is controe* then the *esire* ener-y can e pro*/ce .hich +ay e /se* ,or /se,/ p/rpose ie ,or proton o, eectricity in n/cear reactor
K CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
usion &eaction:
& reaction in .hich t.o i-ht n/cei ,/ses to-ether to ,or+ a hea6y n/ce/s .ith the reease o, a ar-e a+o/nt o, ener-y is cae* n/cear ,/sion reaction E!planation:
/sion reaction is the re6erse o, ssion reaction In ,/sion reaction the ener-y reease* is +/ch +ore as co+pare* to that o, ssion reaction I, an ato+ o, *e/teri/+ is ,/se* .ith an ato+ o, Triti/+ then a hei/+ n/ce/s or apha partice is ,or+e*4 neary 1GE 'e7 o, ener-y is ierate* This process is epresse* as5 0 2
1
+
2
0e 4
0 3
2
+
0
n1
+ &
The +ass o, hei/+ n/ce/s an* ne/tron is ess than that o, *e/teri/+ an* triti/+ The *eciency o, the +ass con6erte* to ener-y thro/-h !instein +ass ener-y e
It is 6ery *ic/t to pro*/ce a ,/sion reaction #hen n/cei are ro/-ht rear each other ,or ,/sion5 .or; has to e *one to o6erco+e the eectrostatic ,orce o, rep/sion et.een the t.o n/cei5 .hich re
N/cear ra*iations can e *an-ero/s to h/+an o*y5 */e to careess in its /se eca/se these ra*iations are in6isie They can *a+a-e o/r o*y ces */e to its ioni?ation property !cessi6e ra*iations +ay ca/se cancer or inc/rae ra*iation +ay ca/se cancer or inc/rae ra*iation sic;ness to h/+an ein- I, a person hi-hy ra*iate* +ay s/Der ,ro+ the ,oo.in- *iseases 1 2 3 =
&ne+ia Boo* cancer 'ai-nant t/+or Cataracts (Opticay o, ens o, eyes)
"recautions against (uclear radiation:
1 #e sho/* stay a.ay ,ro+ ra*ioacti6e so/rce5 eca/se these ra*iation sprea* in a *irection 2 The *octors sho/* /se the ra*iation ,or +ini+/+ possie */rin- the treat+ent 3 O6er*ose o, ra*iations sho/* a6oi*e* = The n/cear .aste sho/* e /rie* ,or a.ay ,ro+ the resi*entia areas #e sho/* /i* a thic; .a concrete aro/n* the reactor to protect o/rse6es ,ro+ ra*iations E #e sho/* /se + a*-e an* *osi+eter */rin- the *eter+ination o, intensity o, ra*iations G #e sho/* pace the ra*ioacti6e +aterias in a o ea*
KK CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& The person sho/* chec; the+se6es +e*icay on re-/ar asis .ho is .or;in- in n/ce/s aoratory 9ses of radioisotopes:
Ra*io isotopes are 6ery /se,/ in +e*icine5 &-ric/t/re5 In*/stry5 "eoo-ica *atin- an* archeoo-y etc Medicines:
1) 2) 3) =) ) E) G)
To st/*y the .or;in- o, interna or-ans or the treat+ent o, +any co+picate* *iseases To trace o/t circ/ation o, oo* in the o*y or sterii?in- instr/+ents an* s/r-ica toos To contro cancer To contro ecessi6e pro*/ctions o, .hite oo* ces in the o*y To trace o/t path o, an ee+ent in the o*y o, pants5 ani+as an* h/+an ein-s
'griculture:
1) 2) 3) =) )
or preser6ation o, ,r/its5 6e-etaes an* other ,oo* st/D To ;i acteria an* other har+,/ insects Can e /se* as ,ertii?ers To st/*y the process o, photosynthesis in pants To +eas/re the rate o, -ro.th o, roots o, a pant
%ndustry:
1 2 3 = E
In the +an/,act/rin- o, +achine toos To n* the thic;ness o, *iDerent +aterias To ocate an* re+o6e ,a/ts in +achine To trace o/t the ea;a-e o, pipes To trace o/t the crac;s in .e*e* Joints To esti+ate the .ear an* tear in +achine toos
Ieological dating:
P923 *ecays to ea*920E The ratio o, /923 to ea*920E present in a roc; can e /se* to *eter+ine the a-e o, the roc;
2onceptual uestions: $. 4hat type of charge is present on.
+a
A
@
? ?rays +b
?rays +c
?rays;
&ns: ? a The
9partices are *o/e positi6e char-e* partices The posses o. penetratin- po.er an* hi-h ioni?ation eDect They can e *eecte* y +a-netic an* eectric e* @
b The
9partices are ne-ati6ey char-e* partices They posses hi-h penetratin- po.er an* o. ioni?ation The eectric an* +a-netic e* can aDect the path o, those rays8partices A
c The
9 partices are ne/tra partices There is no eDect o, eectric an* +a-netic e* on the path o, those partices They can tra6e .ith 6eocity o,
100 CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'& i-ht an* th/s posses’ 6ery hi-h penetratin- po.er an* 6ery o. ioni?ation eDect .*: 4hat are the sources of energy from sun and stars; 'ns: The te+perat/re o, s/n an* other stars is etre+ey 6ery hi-h /e to .hich
hi-h te+perat/re5 ,/sion reaction occ/rs at s/n s/r,ace an* stars 6ery easiy /rin- ,/sion reaction5 tre+en*o/s a+o/nt o, ener-y is reease* Th/s the ,/sion reaction is cheaper so/rce o, ener-y ,ro+ s/n an* stars -: 'n element “N” ha3ing atomic number “B*” and mass number *-@ emits on d?particle to form another element “D” 4hat 5ill be atomic number and mass number if element “D”.
&ns: #e Fno. that .hen a ra*ioacti6e ee+ent e+its *9partice then the parent ee+ent @_A is con6erte* into a *a/-hter ee+ent @$A the ato+ic n/+er o, the *a/-hter ee+ent is t.o ess .hie its parent ee+ent is ,o/r ess than that o, the parent ee+ent so .e ha6e5 Th/s the ato+ic n/+er o, @$A .i e @K0A an* its +ass n/+er .i e 23= : 4hich of the follo5ing nuclei 5ill be more stable and 5hy; +a B*9*-1 +b$=#-*
&ns: The staiity o, n/cei *epen*s /pon the n/+er o, n/cei "reater the n/+er o, n/ceons ess .i e the staiity o, the n/cei an* 6ice 6ersa Th/s @1ES32A .i e +ore stae than K2P23 eca/se the n/+er o, n/ceons in @1ES32A is ess than the n/+er o, n/ceons in @ K2P23A 1: 2omplete the follo5ing reaction; 9
B*
*-1
Jn
$
Ka
1=
$-B
>r Jn$
&ns: The ao6e reaction represents ssion reaction in .hich ne/tron is o+ar*e* on /rani/+ an* th/s a co+po/n* n/ce/s is ,or+e* Th/s co+po/n* n/ce/s is 6ery +/ch /nstae an* spits to -i6e ari/+ @BaAFrypton@FrA three ne/trons an* ener-y #e ;no. that in e6ery n/cear reaction the +ass n/+er an* char-e n/+er o, reaction an* pro*/cts re+ain the sa+e So in ao6e reaction5 the +ass no o, @FrA .i e >K=’ an* its char-e n/+er .i e @3EA The co+po/n* n/ce/s is represente* y `K2 P 23E5 so the co+pete reaction can e .ritten as4 0
n1
+ 52 > 23&
(a 141 +
&
Kr 52
3
4ritten and composed by: Cahoor 'hmad M.#c. "
+3 0 n 1 + *
101 CH&T!R NO 1 NORTH HILLS SCHOOL COLL!"! #RITT!N B$: %&HOOR &H'&
