PAPER 2 SECTION B Question 1
Diagram 9.1 and 9.2 show two types of catapult.
Before After
Diagram 9.2 (a)
Before After
Diagram 9.2(b)
(a) What type of energy is stored when the rubber is pulled?
Elastic potential energy
[1 mark] (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
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] (iii) State the energy change and
deduce a relevant physics concept. Elastic potential energy to kinetic energy.
Principle of conservation of energy. [2 marks] (c) Using a catapult, explain how to
enable a stone to travel a longer distance.
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.
Using appropriate physics concepts, explain the use of suitable equipment
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 Reason
strong material Do not break easily Small mass To increase speed /
lighter Streamline Reduce air
resistance Run faster Increase kinetic
energy Throw at an
angle of 45°
To get maximum horizontal distance Throw with high
force
To get maximum horizontal distance
Question 2
Diagram 9.1 and Diagram 9.2 show the water spurt from two identical
containers P and Q.
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
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
(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]
(c) An efficient hydraulic brake system is very important in a car for safety purposes.Diagram 9.4 shows a car hydraulic brake system.
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 Explanation Oil Incompressible/ No air bubble High boiling point/ Low density/ High viscosity
Does not change to gas state/
Lighter/ Less friction/
Does not evaporate easily
Small master piston
High pressure produced/
Small force used Big slave piston Produce big force
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 ure before heating / o C Temperat ure after heating / o C Specif ic heat capac ity / Jkg-1 o C-1 Alumini um dust 35 50 900 Copper dust 35 70 380
[ 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.
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 ]
Suggestions Reason
Add more ice Large mass of ice can absorb more heat from the drinks. Add water to
the ice
Increase the rate of heat transferred through conduction. Container made of heat insulator To reduce heat absorbed from the surrounding. Container made of substance with high specific heat capacity
Not easily heated up.
Use white container
Do not absorb heat
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.
Diagram 10.1
Diagram 10.2 shows the experiment is repeated by changing loudspeakers distance
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
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. 1st : 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. [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.
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.
4th : 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.
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]
Modification Reason
Microwave Energy of the
microwave is converted to heat Transmitter is
located at the center of the oven
The heat can be distributed uniformly to the food
The material of the food tray is made of porcelain / glass / heat resistant Can withstand high temperature in the oven
The shape of food tray is circular
So it can be
rotated easily and continuously. The food can absorb heat uniformly. The casing is
made from metal
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’.
(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) The induced current produced in the secondary coil. [2 marks]
When the induced current (produced) is increases, the brightness of bulb increases
(c)(i) Explain how induced current is produced at secondary circuit. Diagram 10.1
Diagram 10.2 Bulb ‘24V, 36W 12V a.c power supply
Iron core
Coil
12V a.c power supply
Iron core
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
Use soft iron core // Use thicker wire of conductor// Use laminated core // Winding the secondary and primary on top of each other
[1 mark] (d) Diagram 10.4 shows a cross
section of a moving coil microphone.
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
(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 REASONING use thin diaphragm Easy to vibrate Use strong material
Not easy to break
More number of turns of coil
Increase the rate of change of magnetic flux linkage // The magnitude of the induced current or is also increased Thicker diameter of wire of coil
Reduce the resistance of the coil
Using more powerful magnet
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.
(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] (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.
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.
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.
(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]
(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] (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
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 ] Suggestion Explanation i) -Use forceps/robot The distance between the source and the body is far. Wear a mask//
goggle
The radiation does not penetrate our eyes
Use a lead box/ container with thick concrete
To prevent
radiation leakage to surroundings Keep the exposure
time as short as possible
The body is not exposed to the radiation for a long time. - Wear a film badge To detect the amount of radiation exposed Put radiation symbol on the storage box To inform users of dangerous contents of the box.
Wear coat lined with lead
To protect the body from the radiation
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]
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
(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
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 REASONING
Small angle Produce bigger resultant force
Streamlined Reduce
resistance Steel Rod Strong// able to
withstand high tension
Inelastic Produce uniform force during the towing. Arrangement K is chosen 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
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]
F = ρVg = 1020 x 10 x 5 = 51 000 N
Total weight = Bouyant force 15 000 + W = 51 000
W = 36 000 N
(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 S
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 Reason
Fibre composite Light and strong Bigger volume High buoyant
force The distance
between plimsoll line from the surface of the sea is high
Can carry more load
Bigger size of the propeller
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
Diagram 11 shows the phenomenon of sea breeze during the sunny day. The sun transmit ray in the form of heat and light.
Diagram 11.1
(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
2nd : 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.
(i) What is the melting point of the substance X?
77 °C
[1 mark] (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 2nd : t = 300 s 3rd = 5 minute 4th : T = 3 + 5 = 8 minute
(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.
Diagram 11.3
Table 11 shows the characteristics of four different radiators.
Radiat Control Colour Boiling Po
or unit of radiator surface Point of heating liquid wer W Automatic Silver 100 oC 3.0 kW X Manual Black 100 oC 1.5 kW Y Manual Silver 300 oC 3.0 kW Z Automatic Black 300 oC 1.5 kW 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]
Characteristic Reason
Automatic control unit
The heater will switch off if the room is very hot. Black colour of
radiator source
good heat absorber and transmitter High boiling point
of heating liquid
The liquid will not change to gas easily.
Low power 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.
Question 11
Diagram 12.1 shows a ping-pong ball placed between two electrodes.
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?
1st : 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.
Diagram 12.2
(c) Table 12 shows 5 heating elements M,N,O,P and Q with characteristics to used as an effective bread
toaster heater.
Table 12
(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 Heating element/ Size of wire /swg Resistivity / Ωm Specific Heat Capacity / Jkg-1 o C-1 Length / m M 15 2.0 x 10-8 900 2 N 30 10.0 x 10-8 390 3 O 15 8.0 x 10-8 450 2 P 30 6.0 x 10-8 440 3 Q 15 7.0 x 10-8 390 2
heating element. Give a reason for your choice [10 marks] Characteristics Reason Size of wire is small High resistance
Resistivity is high produce more heat
Low specific heat capacity
Heat up faster
Long wire High resistance
Choose heating element N
Because the size 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.
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
(iii) Energy released by the bulb
[5 marks]
Question 12
Diagram 12.1 shows an electrical circuit.
Diagram 12.1
(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 .
Slider Q
Electrical energy to heat energy to light energy
[1 mark] (iii) Draw the diagram of circuit in
Diagram 12.1 using symbols. [1 mark]
(b). Explain why the brightness of the bulb increases when the slider is adjusted close to Q. [2 mark] Length of wire decreases. Resistance decreases. Current increase
(c) Diagram 12.2 shows an electric circuit consist of two bulbs R and S labeled 6V 3W and 6V 12W respectively connected to a 6V battery.
Diagram 12.2
When the switch is turn on, calculate:
(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.
Using your knowledge about electrical 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. Power stesen Janakuasa Transformer P Transformer P ppp Transformer Q Transformer Q Consumer Electric Cable Kabel elektrik
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 Reasoning P step up, Q step down P to increase voltage, Q to decrease voltage to consumer
Big Diameter Reduce resistance
Current with high voltage Small current flows // Reduced power/ heat loss
Cable on pylon Safety reason L is chosen 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.
Sys-tem 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 N P is step up Q is step up Small diameter Conductor Current with higher voltage On concrete piller
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:
(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 explanation
Curved shape 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
(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.
(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.
(a) What is meant by radioisotope? Isotope which is radioactive
(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
(c) The following equation shows the decay of a radioactive substance.
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
(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. Radio- Isotopes State of matter Type of ray Half-life Penetra- ting power J solid Beta 12 years Medium K Solid Gamma 5 years High L Solid Alpha 19 days Low N Gas Beta 5 years 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 reason
Solid Easy to handle
Beta Can penetrate the
paper
Long half life Do not need to replace the radioactive substance frequently, save cost
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.
[2 marks] (iii) Name the physical quantity that represents the value in (a)(ii).
……….... [1 mark] V/volt Graph of V against I Graf V melawan I 2.5 2.0
(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 = ………..
(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?
... [1 mark] (ii) Determine the value of l when m = 0 g.
Show on the graph , how you determine the value of l.
l = ... [2 marks]
(b) The spring constant, k, is given by the formula , where h is the gradient of the graph.
(i) Calculate the gradient, h, of the graph. Show on the graph how you calculate h.
h = ... [3 marks]
Graph of l against m Graf l melawan m
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’ = ………. [3 marks] (d) State two precautions that can be taken to improve the accuracy of
the readings in this experiment.
1. ... 2. ... [2 marks]
