Measurements and Instrumentation Objective Questions with Answers: Part-9 MEASUREME!S A" IS!RUME!A!IO O#$E%!I&E QUES!IOS 'I!( AS'ERS
[1] A rectifier type instrument is connected to 100VDC and is operated in the DC measuring module reads (a) 111V (b) 90V (c) 0V (d) 100V Ans: A
Ans!er ["] A permanent magnet mo#ing coil ammeter has a coil resistance of 99ohm and $ull %cale Deflection($%D) current of 0&1mA& %hunt resistance is 1 ohm& Current through the meter m eter at 0& $&%&D $&%&D is (a) 0&00'mA (b) 0&0mA (c) 0&0"mA (d) 0&1mA Ans: B
Ans!er [] ne single phase !attmeter operating on "0V and A for hours ma*es 19+0 re#olutions& ,eter constant in re#olutions is +00& -hat is the po!er factor of the land. (a) 1 (b) 0&/+ (c) 0&' (d) 0& Ans:B
Ans!er [+] $or po!er measurement of three phase circuit by t!o !attmeter method !hen the #alue of po!er factor is less than 0& lagging (a) one of the !attmeters !ill read 2ero (b) both gi#e the same readings (c) one of the !attmeter connections !ill ha#e to be re#ersed (d) pressure coil of the !attmeter !ill become ineffecti#e& Ans:C
Ans!er [] -hen using ohmmeter applied #oltage is to be disconnected from the circuit because (a) Voltage source !ill increase resistance
(b) Current !ill decrease resistance (c) the ohmmeter has its o!n internal battery (d) non of the abo#e Ans: C
Ans!er [] -hich !a#e has the least form factor. (a) %3uare !a#e (b) 4ectangular !a#e (c) %ine !a#e (d) 5riangular !a#e Ans: A
Ans!er ['] -ith a s!eep time 10ms across the screen the appro6& hori2ontal sa!tooth fre3uency !ill be (a) 072 (b) 10072 (c) 1*72 (d) 0072 Ans: B
Ans!er [/] A spring controlled indicating instrument has a deflection of 90deg for ma6imum current 8& 5he corresponding deflection for a gra#ity controlled instrument is (a) 90 (b) 1"0 (c) 0 (d) 0 Ans: C
Ans!er [9] 8t is found that 10A current passes through a resistor of 10ohms& 5he resistor has : tolerance & 5he error in measurement of current can be as high as :& -hat is ma6 error in measurement of po!er calculated from measured #alue of 8 and the nominal #alue of resistor. (a) 100 (b) 10(c)0(d) "00Ans: B
Ans!er [10] A resistor of 10;ohms !ith : tolerance is connected in parallel !ith a ;ohms resistor of 10: tolerance& -hat is the tolerance limit for the parallel net!or*.
(a) : (b) &': (c) 10: (d) /&: Ans: D
Ans!er [11] 5he resistance offered to the passage of an in<#arying current by a column of mercury at the temperature of melting ice of mass 1+&+"1 gms of uniform cross< sectional area and length 10&cm is (a) %tandard ohm (b) ne international ohm (c) ne ohm according to %8 units (d) ne ohm according to !or*ing standards Ans: B