1 PAPER 2 SECTION B Question 1 Diagram 9.1 and 9.2 show two types of catapult.
stone is the same.) State the relationship between the thickness of the rubber used and the distance travelled by the stone, D. The distance travelled by the stone in Diagram 9.2(b) is longer than in Diagram 9.2(a). The ticker the rubber used, the longer the distance travelled by the stone. [2 marks]
Before
(iii) State the energy change and deduce a relevant physics concept.
After
Elastic potential energy to kinetic energy. Principle of conservation of energy. [2 marks]
Diagram 9.2 (a) Before
(c) Using a catapult, explain how to enable a stone to travel a longer distance.
After
Diagram 9.2(b) (a) What type of energy is stored when the rubber is pulled? Elastic potential energy [1 mark]
Use ticker rubber to increase the elastic potential energy. Stretch the rubber longer to increase elastic potential energy. Use stone with smaller mass to increase the speed of the stone. Use a strong material to the handle of the catapult so that it will not break easily. [4 marks] Diagram 9.3 shows an athlete throwing a javelin.
(b) (i) Based on Diagram 9.1(a) and 9.1(b), compare the thickness of the rubber used. Rubber in Diagram 9.1(b) is thicker than in Diagram 9.1(b). (ii) From Diagram 9.2(a) and 9.2(b), compare the distance travelled by the stone, D when it is pulled with the same extension, x. (Assume the mass of the
Using appropriate physics concepts, explain the use of suitable equipment
2 and techniques to improve his performance. Your answer should include the following aspects: (i) Materials used for javelin. [4 marks] (ii) Shape of javelin [2 marks] (iii)Motion of the athlete [2 marks] (iv)How the javelin should be thrown. [2 marks] Modification strong material Small mass Streamline Run faster Throw at an angle of 45° Throw with high force
Question 2 Diagram 9.1 and Diagram 9.2 show the water spurt from two identical containers P and Q.
Reason Do not break easily To increase speed / lighter Reduce air resistance Increase kinetic energy To get maximum horizontal distance To get maximum horizontal distance
Diagram 9.1
Diagram 9.2 The density of water in container P and container Q is equal. (a) What is the meaning of density? Mass/volume
[1 mark]
(b)(i) Using Diagram 9.1 and Diagram 9.2, compare the depth of the
3 holes, the distances of spurt of water and the pressure exerted on the holes. 1.The depth of hole in Diagram 9.2 > Diagram 9.1 2. The distance of spurt of water in Diagram 9.2 > Diagram 9.1 3. The water pressure in Diagram 9.2 > Diagram 9.1 [3 marks] (ii) State the relationship between the pressure and (a) the depth of the hole. The deeper the hole the higher the pressure
(c) An efficient hydraulic brake system
is very important in a car for safety purposes.Diagram 9.4 shows a car hydraulic brake system.
(b) the distance of spurt of water. The higher the pressure the further the spurt of water. [2marks] (c) Diagram 9.3 shows a Bunsen burner.
Diagram 9.3 Explain how the Bunsen burner can produce a blue flame. 1. The speed of jet of gas is high 2. As the speed of gas high the pressure is low 3. The atmospheric pressure is higher than pressure inside // there is difference in pressure. 4. Air from outside enter 5. Complete combustion occurs. [4 marks]
Suggest and explain the modification should be done on the system so that it can function effectively based on the following aspect : (i) The type material of brake fluid. (ii) The characteristic of brake fluid. (iii) The size of master piston (iv) The size of slave piston. (v) The type material of the fluid transmission pipe. [10 marks] Modification/ suggestion Oil
Explanation
Big slave piston
Incompressible/ No air bubble Does not change to gas state/ Lighter/ Less friction/ Does not evaporate easily High pressure produced/ Small force used Produce big force
Aluminium/
Strong/
High boiling point/ Low density/ High viscosity
Small master piston
4 Steel
Does not break easily/ Non corrosive/ Prevent leakage/ Withstand temperature/ Does not rust easily
Question 3 Figure 9.1 shows two test tubes containing aluminium dust and copper dust of the same mass but having different specific heat capacity. Both the test tubes are heated with the same rate for a same period of time.
Diagram 9.1 Table 9.2 shows some important data for aluminium and copper dust. (a) (i) What is meant by specific heat capacity ? Amount of heat required to the substance to increase its temperature by 1oC for a mass of 1kg. [ 1 mark ] (ii) Using the information given in Table 9.2, compare the temperature rise and the specific heat capacity of aluminium and copper dust. Relate the amount of heat supplied with the temperature rise for aluminium and copper dust. Hence
state the relationship between specific heat capacity and the amount of heat required for the same temperature rise of a substance. 1. Aluminium is heated up slower than copper. // Aluminium has a lower temperature rise // vice versa. 2. Specific heat capacity for aluminium is higher than that for copper// vice versa. 3. For the same amount of heat supplied, aluminium has a smaller temperature rise. 4. Aluminium requires more heat to raise the temperature by 1oC// vice versa 5. Amount of heat required for the same temperature rise increases when the specific heat capacity of a substance increases. [ 5 marks ] (b) Explain why the body of a cooking pot is made of good heat conductor whereas the handle of the pot is made of poor heat conductor. 1. Good heat conductor has a smaller specific heat capacity. 2. Hence the body of the cooking pot can be heated up very fast. 3. Poor heat conductor has a larger specific heat capacity. 4. Hence the handle may absorb a great amount of heat without a high increase in temperature// will not become too hot. Temperat Temperat Specif ure ure after ic before heating / heat o heating / C capac o C ity / Jkg-1 o -1 C Alumini um dust Copper dust
35
50
900
35
70
380
5 [ 4 marks ] (c) A family is having a picnic at Port Dickson beach. An open aluminium container with some ice cubes is used to cool the packet drinks as shown in the Figure 9.2. Question 4 Diagram 10.1 shows apparatus arrangement to investigate a phenomenon of sound wave. A student is requested to walk in a straight path at a distance from the loudspeakers.
Use appropriate concepts in physics, explain the modifications required to the above aluminium container so as to work effectively. (i) cool packet drinks in a shorter time. (ii) keep the packet drinks remain cold for a longer period. [ 10 marks ] Reason Large mass of ice can absorb more heat from the drinks. Add water to Increase the rate of the ice heat transferred through conduction. Container To reduce heat made of heat absorbed from the insulator surrounding. Container Not easily heated up. made of substance with high specific heat capacity Use white Do not absorb heat container
Diagram 10.1 Diagram 10.2 shows the experiment is repeated by changing loudspeakers distance
Suggestions Add more ice
Diagram 10.2 (a)(i) What type of wave is the sound wave? Sound wave is a longitudinal waves. [1 mark] (ii) Based on Diagram 10.1 and Diagram 10.2, compare the distance between two
6 Loudspeakers, the distance between the loudspeakers and the position where loud and soft sound can be heard and the distance between two consecutive loud sounds. Relate the distance between two loudspeakers with the distance between two consecutive loud sounds.Name the wave phenomenon involved. st 1 : The distance between two loudspeakers in Diagram 10.1 is shorter than in Diagram 10.2 2nd : The distance between two loudspeakers and the position where the loud and soft sound can be heard are equal. 3rd : The distance between two consecutive loud sounds in Diagram 10.1 is larger. 4th : The distance between two loudspeakers is inversely proportional to the distance between two consecutive loud sounds. 5th : Wave phenomenon is interference.
1st : The sound wave can be heard because it can bend / diffracted around the corner. 2nd : Sound wave has longer wavelength than light waves. 3rd : The diffraction of sound wave is more obvious / easier than light waves. th 4 : The effect of diffraction is more obvious if the wavelength is large enough. [4 marks] (c) Diagram 10.4 shows an electric
oven is being used to heat up food which has been taken out from a refrigerator.
[5 marks] (b) Diagram 10.3 shows a radio is placed near the corner of a wall. A boy is standing around the next corner.
Diagram 10.3 When the radio is switched on, the boy can hear the sound from the radio but he cannot see the radio. Explain this situation.
You are required to modify the design in Diagram 10.4 by using an electromagnetic wave and a transmitter so that the food can be heat up uniformly and in a shorter time. State and explain the modification based on the following aspects: - The type of electromagnetic wave used - The position of the transmitter. - The material of the food tray. - The shape of the food tray. - The material used for the oven casing [10 marks]
7
12V a.c power supply
Iron core Modification Microwave
Transmitter is located at the center of the oven The material of the food tray is made of porcelain / glass / heat resistant The shape of food tray is circular
The casing is made from metal
Reason Energy of the microwave is converted to heat The heat can be distributed uniformly to the food Can withstand high temperature in the oven
So it can be rotated easily and continuously. The food can absorb heat uniformly. Can reflect microwave
Question 5 Diagram 10.1 and Diagram 10.2 show two coils of identical wire wound around an iron core. The primary coil is connected to 12V a.c power supply, while the secondary coil is connected to a bulb labeled ‘24V, 36W’. 12V a.c power supply
Coil Bulb ‘24V, 36W Diagram 10.2 (a)What is the meaning of ‘24V, 36W’? 36 J of energy is consumed in 1 s if connected to a 24 V power supply [1 mark] (b)Observe Diagram 10.1 and Diagram 10.2, compare; (i) The brightness of bulb (The brightness of bulb) in D10.2 is brighter than D10.1 (ii) The number of turns in the primary coil and secondary coil The number of turns of the primary coil is equal The number of turns of the secondary coil in D10.2 is bigger than D10.1 [3 marks] (c) Relate the brightness of bulb with: (i) The number of turns in secondary coil When the number of turns in secondary coil is bigger (than primary coil), the bulb is brighter (ii)
Iron core
The induced current produced in the secondary coil. [2 marks]
When the induced current (produced) is increases, the brightness of bulb increases
Coil Diagram 10.1
(c)(i) Explain how induced current is produced at secondary circuit.
8
When an ac current flows in the primary coil, an alternating magnetic field is produced inside the iron core There is a change in the magnetic flux (direction and magnitude) which is linkage to the secondary coil Produce induced current in the secondary voltage. [3 marks] (ii) State one way to increase the efficiency of a transformer
(ii) strength of the material for diaphragm (iii)number of turns of coil (iv)diameter of the wire of coil (v) strength of magnet [10 marks]
ASPECT use thin Use soft iron core // Use thicker wire of diaphragm conductor// Use laminated core // Use strong Winding the secondary and primary on material top of each other More number [1 mark] of turns of coil (d) Diagram 10.4 shows a cross section of a moving coil microphone. Thicker diameter of wire of coil Using more powerful magnet
Diagram 10.4 When the diaphragm moves in response to sound, the attached coil moves in the magnetic field and generates a very small current in the wire of the coil. Using an appropriate concept in physics, suggest and explain suitable modifications or ways to enable the microphone to detect sound more effectively and generate a bigger current based on the following aspect: (i) thickness of diaphragm
REASONING Easy to vibrate Not easy to break Increase the rate of change of magnetic flux linkage // The magnitude of the induced current or is also increased Reduce the resistance of the coil The magnitude of the induced current is also increased
Question 6 Diagram 10.1 and 10.2 show the atomic structure of two elements commonly used in the manufacture of a type of semiconductor.
(a) What is the meaning of semiconductor? [1 mark] A material with electrical conductivity between conductor and insulator.
9 (b) State the number of valence electrons in Diagram 10.1 and 10.2. When Boron is added to Silicon, majority charge carrier is formed. Name the majority charge carrier. Relate the majority charge carrier with the type of semiconductor produced. Name the physics process to create this type of semiconductor. Diagram 10.1 = 4 Diagram 10.2 = 3 Majority charge carrier = hole Type of semiconductor = p type Doping process. [5 marks]
A shadow is formed because some electrons are stopped by the Maltese cross.
(d) Diagram 10.4 shows the screen of a cathode ray tube (CRO) with an alternating input voltage of 240 V. The CRO is connected to box P which in turn is connected to a hand phone.
(c) Based on Diagram 10.3, explain how a shadow is formed on the screen of a Maltese Cross Tube when the Extra High Tension (E.H.T) power supply is switched on. [4 marks]
The metal/cathode/ filament is heated and electrons are emitted from the metal surface. The extra high voltage between the cathode and the anode causes the electrons to accelerate to the screen. When the electrons hit the screen, the kinetic energy of the electrons is converted by the fluorescent coating to heat and light energy of the screen.
Suggest and explain the suitable circuit for box P so it is suitable for charging the hand phone. Include in your answer: (i) the device used to charge the 9 V hand phone. (ii) The component used to convert alternating current to direct current. (draw the complete circuit with input and output). (iii) The component used to smoothen the output voltage and how it is connected in the circuit.
10 (iv)
Draw the final wave form obtained. [10 marks]
To charge the handphone: A step down transformer is used. To decreases voltage from 240 V to 9 V. To convert ac to dc: 4 diodes is used to form full-waved rectifier.
Use capacitor To smooth the output voltage.
Question 7 Diagram 10.1 and Diagram 10.2 show the decay graphs of two difference radioactive sources .
(a). What is the meaning of radioactivity? Radioactivity is the spontaneous disintegration of unstable nucleus accompanied by the emission of energetic particles or photons [1 mark] (b) Using Diagram 10.1 and Diagram 10.2, compare the initial activity of the sources, the time interval for the activity to be halved and the rate of decay of the radioactives. 1. Initial activity is the same 2. time interval in Diagram 10.1 is longer 3. rate of decay in Diagram 10.1 is lower [3 marks]
(c). State the relationship between:
11 (i) the rate of decay of the radioactive and the time of interval for the radioactive to be halved. The higher the rate of decay the shorter the time interval (ii) half life and the rate of decay of the radioactive. The higher the rate of decay the shorter the half life [2 marks]
method shown is not safe. Suggest and explain; (i). The equipment to be used in handling a radioactive source. (ii) Modifications to the storing method to ensure safe keeping of the radioactive source. (iii) Other precautions that need to be taken when handling a radioactive source. [ 10 marks ]
(d) Uranium-238 decays to Thorium (Th) by emitting an alpha particle. (i) Write the nuclear equation expressing the alpha decay of [2 marks]
(ii) What happens to the proton number and neutron number of U-238 after the decay process? [2 marks] The number of proton will decreases by 2 The number of neutron will decrease by 2
(e). Diagram 10.3 shows a radioactive source is handled by a scientist. The
Suggestion i) -Use forceps/robot
Explanation The distance between the source and the body is far. Wear a mask// The radiation does goggle not penetrate our eyes Use a lead box/ To prevent container with radiation leakage thick concrete to surroundings Keep the exposure The body is not time as short as exposed to the possible radiation for a long time. - Wear a film To detect the badge amount of radiation exposed Put radiation To inform users of symbol on the dangerous storage box contents of the box.
12 Wear coat lined with lead
To protect the body from the radiation
Sum of two or more forces to produce a single force (b) Based on Diagram 11.1: (i) Sketch the resolution of force 1200N for towing boat 1 to its components . [1 mark]
(ii) Calculate the horizontal component of force acting on towing boat 1. [2 marks] Fx = F Cos 20 = 1200 x 0.9397 = 1127.63 N
PAPER 2 SECTION C Question 8 Diagram 11.1 shows a cargo ship is being towed by two towing boats using the same force 1200N each. The resultant force from the two boats cause the cargo ship to move forward.
Diagram 11.1 (a) What is the meaning of resultant force? [1 mark]
(iii)Calculate the resultant force acting on the cargo ship [2 marks] Resultant force = 2 F Cos 20 = 2 x 1127.63 = 2255.26 N (c) Explain why a cargo ship has to switch off her engine a few kilometer from the harbour and has to be towed to the harbour. friction in water is minimum ship still moves forward although the engine stops due to the inertia of the ship has to be towed to its location when it has come to a complete shop
13 Study the specification of the four arrangement based o the following aspects: (i) the angle of the two towing boat (ii) the shape of the towing boats (iii)type of cable rope used. (iv)the elasticity of cable used. Explain the suitability of each aspect and then determine the most suitable arrangement. Give a reason for your choice. [10 marks] ASPECT Small angle Streamlined Steel Rod
Inelastic
Arrangement K is chosen
REASONING Produce bigger resultant force Reduce resistance Strong// able to withstand high tension Produce uniform force during the towing. Big angle, Streamlined, Steel Rod, Inelastic
Question 9 Diagram 11.1 shows the air balloon which is used as a weather balloon to carry a radiosonde instrument for collecting data about the atmosphere. The weather balloon rises up in the air due to Archimede’s Principle.
Method J
Method K
Method L
Method M
14 F = ρVg = 1020 x 10 x 5 = 51 000 N Total weight = Bouyant force 15 000 + W = 51 000 W = 36 000 N
Diagram 11.1 (a) (i) State Archimedes’ principle.
When an object is submerged partially or fully in fluid, the weight of fluid displaced is equal to the buoyant force. [1 mark] (ii) Explain why a weather balloon that is rising up in the air will stop at certain altitude. Volume of air displaced is equal to the volume of a balloon. Density of air decreases as an altitude increases. Weight of displaced air becomes smaller. At certain height, weight of displaced air equal to weight of the balloon. Buoyant force equal to the weight of the balloon. [4 marks] (b) (i) The weight of a boat is 15 000 N and the volume of the immersed portion of the boat is 5.0 m3. Calculate the buoyant force exerted to the boat. [density of sea water is 1020 kg m-3] (ii) A heavy box is put on the boat. Calculate the maximum weight of the box so that the boat will not sink completely. [5 marks]
(c) Diagram 11.2 shows four boats, P, Q, R and S, with different specifications. You are required to determine the most suitable boat that can carry many passengers, move with high speed and safe. Study the specifications of all the four boats from the following aspects. - The material used to build the body of the boat. - The volume of the boat. - The distance of the Plimsoll line from the surface of the sea. - The size of the propeller. Boat P
Boat Q
Boat R
15 Diagram 11 shows the phenomenon of sea breeze during the sunny day. The sun transmit ray in the form of heat and light.
Boat S
Diagram 11.1
Explain the suitability of the above aspects and hence, determine the most suitable boat to carry heavy load and move with high speed. Justify your choice. [10 marks] Characteristics Fibre composite Bigger volume The distance between plimsoll line from the surface of the sea is high Bigger size of the propeller
Reason Light and strong High buoyant force Can carry more load
To produce greater forward thrust Q is choosen because the body is made from fibre composite, bigger volume (100 m3), the distance between plimsoll line from the surface of the sea is high and bigger size of the propeller.
Question 10
(a) (i) What is the meaning of heat? Heat is a form of energy. [1 mark]
(ii) Explain the phenomenon of sea breeze during daylight. 1st : Land has a smaller specific heat capacity than sea / land is warmer than the sea nd 2 : Air above the land is heated up and rises. 3rd : The pressure above the land is low. 4th : Cooler air from the sea moves towards the land as sea breeze. [4 marks] (b) Diagram 11.2 shows the heating curve of a solid substance X of mass 0.5 kg using an immersion heater of 50W.
16 or
W
X
Y
(i) What is the melting point of the substance X? Z 77 °C [1 mark]
unit
of radiator surface
Point wer of heating liquid
Automatic
Silver
100 oC
3.0 kW
Manual
Black
100 oC
1.5 kW
Manual
Silver
300 oC
3.0 kW
Automatic
Black
300 oC
1.5 kW
(ii) Calculate the value of T if the specific latent heat of fusion of the substance X is 3 x 104 J kg -1. [4marks] Pt = ml 1st : t = (0.5)( 3 x 104) 50 nd 2 : t = 300 s 3rd = 5 minute 4th : T = 3 + 5 = 8 minute
Table 11 Explain the suitability of each characteristic of the radiator and determine the most suitable radiator to be used for the purpose of maintaining the temperature of the small room. Give reasons for your choice. [10 marks]
(c) Diagram 11.3 shows a radiator used to maintain temperature of a small room so that the occupants of the room feel warm during a very cold day.
Characteristic Automatic control unit Black colour of radiator source High boiling point of heating liquid Low power
Diagram 11.3 Table 11 shows the characteristics of four different radiators. Radiat
Control
Colour
Boiling
Po
Reason The heater will switch off if the room is very hot. good heat absorber and transmitter The liquid will not change to gas easily. Save energy / low cost
Choose Z Because it has automatic control unit, black colour of radiator source, high boiling point of heating liquid and use low power.
17 Question 11 Diagram 12.1 shows a ping-pong ball placed between two electrodes.
Diagram 12.2
Diagram 12.1 The electrodes are connected to an Extra High Tenson, E.H.T., hence produces a strong electric field between the electrodes when the switch is on. (a)(i) What is the meaning of electric field? Electric field is a region where a charge experience electric force [1 mark] (ii) What happen to the ping-pong ball as it touches one of the electrodes? st 1 : The ball will receive positive charge from the positive disc. 2nd : Like charges on the disc and the ball repelled each other 3rd : The ball attracted by the negatively charged disc. 4th : The positive charge is neutral when the ball touches the negative disc. 5th : The ball then negatively charged and repels toward positive disc. 6th : The ball oscillates between the two plates. [4 marks] (b) Diagram 12.2 shows heating element In a toaster.
(c) Table 12 shows 5 heating elements M,N,O,P and Q with characteristics to used as an effective bread toaster heater. Heating Size element/ of wire /swg M N O P Q
15 30 15 30 15
Resistivity / Ωm
2.0 x 10-8 10.0 x 10-8 8.0 x 10-8 6.0 x 10-8 7.0 x 10-8 Table 12
Specific Heat Capacity / Jkg-1 o -1 C 900 390 450 440 390
(d) You are required to determine the most suitable element heating that can be used to toast bread fast and crispy. Study the specifications of all the five heating element based on the following aspects (i) Size of wire (ii) Resistance per meter (iii) Specific Heat Capacity (iv) Length of the heating element Explain the suitability of each aspect and then determine the most suitable
Length /m
2 3 2 3 2
18 heating element. Give a reason for your choice [10 marks] Characteristics Reason Size of wire is High resistance small Resistivity is high produce more heat Low specific heat Heat up faster capacity Long wire High resistance Choose heating Because the size element N of wire is small, has high resistivity, has low specific heat capacity and long wire
(e) Three resistors with resistance 1 Ω, 2 Ω, and 3 Ω respectively are connected to 6 V battery as shown in Diagram 12.3.
(iii) Energy released by the bulb [5 marks]
Question 12 Diagram 12.1 shows an electrical circuit. Q
Switch
Slider
Diagram 12.1 Based on Diagram 12.3, calculate (i) Effective resistance
Effective resistance = 1 Ω (ii) Power dissipated by 2 Ω resistor
1st : I = 6/1 = 6 A 2nd : P = I2R = 322 = 18 W
(a)(i) What is the function of rheostat in the circuit? [1 mark] To control resistance / electric current (ii) State the energy transformation occurs at the bulb in the circuit .
19
Electrical energy to heat energy to light energy [1 mark] (iii) Draw the diagram of circuit in Diagram 12.1 using symbols. [1 mark]
(i) the total current in the circuit . [ 3 marks] P = VI I= P V = 3 = 0.5 A 6 Total I = 0.5 x 2 = 1 A (iii) the energy used by a bulb , R in one minute. [2 marks]
E = VIt = 6 x 0.5 x 60 = 180 J (d) National Grid Network is a system of electric transmission from power station to the consumer in our country. Diagram 12.3 shows a block diagram of the system. (b). Explain why the brightness of the Power stesen bulb increases when the slider is Janakuasa adjusted close to Q. [2 mark] Length of wire decreases. Resistance decreases. Current increase Transformer P Transformer P ppp Electric Cable (c) Diagram 12.2 shows an electric circuit consist of two bulbs R and Kabel elektrik S labeled 6V 3W and 6V 12W respectively connected to a 6V Using your knowledge about electrical battery. and Diagram 12.3 , you are asked to determine the most suitable item used in the system J, K, L, M and N for a National Grid Network system in Diagram 12.4.
Diagram 12.2 When the switch is turn on, calculate:
Consumer
Transformer Q Transformer Q
20
System
Type of Transformer
Diameter of conductor cable
Transmission voltage
Cable Position
J
P is step up Q is step down
Big diameter conductor
Current with Low voltage
On the Pylon
K
Q is step up P is step down
Small diameter Conductor
Current with higher voltage
On concrete piller
L
P is step up Q is step down
Big diameter conductor
Current with higher voltage
On the Pylon
M
Q is step up P is step down
Small diameter Conductor
Current with Low voltage
On concrete pylon
P is step up Q is step up
Small diameter Conductor
Current with higher voltage
On concrete piller
N
Diagram 12.4 Study the specification of the five system and explain the suitability of each based on following aspects; (i) type of transformer P and Q (ii) characteristic of cable used (iii)potential difference transmission of electric (iv)The position of cable Explain the suitability of each aspects and determine the most suitable system. Give your reason for your choice. [ 10 marks] Aspect P step up, Q step down
Big Diameter
Reasoning P to increase voltage, Q to decrease voltage to consumer Reduce resistance
Current with high voltage
Cable on pylon L is chosen
Small current flows // Reduced power/ heat loss Safety reason P step up Q step down, Big Diameter, Current with high voltage, Cable on pylon
Question 13 Diagram 12.1 shows a deflection of a centre zero galvanometer pointer when a magnet is pushed into a coil. The deflection indicates that an induced current is produced in the coil.
21
Diagram 12.1 (a) (i) Name the concept involved in
producing the induced current. Electromagnetic induction [1 mark] (ii). The concept involved in 12(a) (i) is also used for a transformer. Explain the working principle of a transformer. [4 marks] 1. An alternating current flows in the primary coil 2. Producing magnetic flux which always change the direction and magnitude 3. The magnetic flux flows to the secondary coil through the soft iron core 4. Cutting / changing of flux occurs thus producing emf / induced current. [4 marks] (b) Diagram 12.2 shows four types of moving coil ammeter, R, S, T and U to measure small direct current. You are required to determine the most suitable moving coil ammeter to measure the small direct current effectively. You are required to determine the most suitable moving coil ammeter to measure small direct current effectively. Study the specification of all the four moving coil ammeters based on the following aspects:
22 (i). The shape of the permanent magnet and core [2 marks] (ii). The material of the core [2 marks] (iii) The stiffness of the hair spring [ 2 marks] (iv) The type of scale of the ammeter [2 marks] Explain the suitability of each aspect and then determine the most suitable moving coil ammeter. Give a reason for your choice. [2 marks] characteristics Curved shape
explanation Produce radial magnetic field Soft iron Easily to magnetised and demagnetised Soft spring Can detect small current // more sensitive // can measured small current Linear scale Uniform deflection // force produced directly proportional to current. T is chosen Curved shape, Soft iron , soft spring and linear scale
(i) If the bulb lights up with normal brightness , determine the ratio of the number of turns in the coil PQ to the number of turns in the coil RS. [2 marks] Np = Vp Ns Vs = 240 12 = 20 (ii) Calculate the output current flowing. [ 1 mark] I = P/V = 60/12 = 5 A (iii) Calculate the input current if the efficiency of the transformer is 80%. [ 2 marks] 80 = Po x 100 Pi 80 = 60 x 100 Ip (240) Ip = 0.3125 A Question 14 Diagram 12 shows a patient who is given an injection of radioisotope Iodine-131 to trace thyroid cancer. A detector is used to detect the activity of the radioactive emission after the injection.
(c) Diagram 12.3 shows a U-shaped soft iron core is wound with insulated copper wire PQ and RS. An a.c. voltage of 240 V is connected at the end of PQ and a bulb 12V ,60W is connected at the end RS.
(a) What is meant by radioisotope? Isotope which is radioactive [1 mark]
23 (b) Explain how Iodine-131 is used in hospital to detect the location of cancer cells. [4 marks] Iodine -131 is injected into the blood stream. Iodine-131 circulating in the blood stream is attracted/absorbed to the thyroid. Radiation detector produces image of the thyroid / nuclear medicine imaging doses (gamma camera) Abnormalities seen in the thyroid image may indicate presence of cancer
(d) As a scientist, you are asked to investigate the characteristics of radioisotopes J, K, L and N that could be used to detect the thickness of paper in a paper factory. Table 12 shows the characteristics of the radioisotopes.
(c) The following equation shows the decay of a radioactive substance. RadioIsotopes
Mass of neutron = 1.008665 u Atomic mass of U-235 = 235.043925 u Atomic mass of Xe-140 = 139.92162 u Atomic mass of Sr-94 = 93.915367 u 1 u = 1.66 x 10-27 kg c = 3.00 x 108 ms-1 (i) What is the mass defect for the radioactive decay? [3 marks] Mass before: (235.043925 + 1.008665) = 236.052590 U Mass after: (139.921620 + 93.915367 + (2 x 1.008665) = 235.854317 u Mass defect = 0.198273 u (ii) Determine the energy produced in joule. [2 marks] E = mc2 = (0.198273 x 1.6 x 10-27) x (3.0 x 108)2 = 3.291 x 10-28 x (3.0 x 108)2 = 2.96 x 10-11 J
Type of ray
Halflife
J
State of matter solid
Beta
K
Solid
Gamma
L
Solid
Alpha
N
Gas
Beta
12 years 5 years 19 days 5 years
Penetrating power Medium High Low high
Using Table 12, describe the characteristics of radioisotope that is suitable to be used in the paper thickness detection system. Determine the most suitable radioisotope to be used to detect the paper thickness and give your reasons. [10 marks] Characteristics Solid Beta Long half life
Medium
reason Easy to handle Can penetrate the paper Do not need to replace the radioactive substance frequently, save cost Suitable to use to
24 measure thickness of paper / reduce danger o radiation to people / no extra shielding needed Choose J because it is solid, emit Beta, long half life, medium penetration power
PAPER 3 SECTION A QUESTION 2 Question 15 A student carries out an experiment to determine the internal resistance, r, of a dry cell. The results of this experiment is shown in the graph of potential difference, V, against current, I, in Diagram 2.1. (a) Based on the graph in Diagram 2.1, (i) What happens to V as I increase ? ………………………………………………………………………………................... [1 mark] (ii) Determine the value of V when I = 0 A. Show on the graph, how you determine the value of V.
V = ……………………………….
25 [2 marks] (iii) Name the physical quantity that represents the value in (a)(ii). ……………………………………………………………………………………….... [1 mark]
V/volt
2.5
2.0
Graph of V against I Graf V melawan I
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(b) The internal resistance, r, of the dry cell is given by the formula r = -m, where m is the gradient of the graph. (i) Calculate the value of m. Show on the graph how you calculate m.
m = …………………………….. [3 marks] (ii) Determine the value of r.
r = ………………………….. [1 mark]
27 (c) From the graph, state the value of V when I = 0.6 A. Show on the graph how you determine the value of V.
V = ……………………………… [2 marks]
(d) State two precautions that can be taken to improve the accuracy of the readings in this experiment. 1…………………………………………………………………………………………………..
2……………………………………………………………………………………..…………... [2 marks]
2. A student carries out an experiment to investigate the relationship between the mass, m, or a load placed on a spring and the length, l, of the spring. The student also determines the spring constant, k. The result of this experiment is shown in the graph of l against m in Diagram 2.1 on page 9. (a) Based on the graph in Diagram 2.1, (i) What happens to l as m increases?
(ii)
...................................................................................................................... [1 mark] Determine the value of l when m = 0 g. Show on the graph , how you determine the value of l. l = ...............................
(b) The spring constant, k, is given by the formula gradient of the graph.
[2 marks] , where h is the
28 (i)
Calculate the gradient, h, of the graph. Show on the graph how you calculate h.
h = .....................................
Graph of l against m Graf l melawan m
[3 marks]
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(ii)
Determine the value of k.
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k = ........................... [1 mark] (c)
Another identical spring is connected in series to the end of the spring. The spring constant, k’, of two springs in series is given by the formula Calculate k’.
k’ = ………………………………. (d)
[3 marks]
State two precautions that can be taken to improve the accuracy of the readings in this experiment. 1. ................................................................................................................. 2. ................................................................................................................. [2 marks]
