SMK RAJA PEREMPUAN, IPOH KOLEKSI E-ESEI (SPM) 2010 PANITIA FIZIK 1.
Diagram below shows waves moving towards a harbour.
a)
b)
i)
What is the meaning of diffraction ?
[1mark]
ii)
Draw the wave pattern of the waves after passing through the entrance of the harbour. [1mark]
The entrance is made wider to allow more ships to enter the harbour. What is the effect on i) the waves passing through the entrance? ii) the harbour?
[2marks] [1mark]
c)
Diagram below shows another modification to the harbour to overcome the heavy sea traffic problem. The wave pattern produced at the entrances is shown in Diagram below.
i)
The wave formed is caused by the superposition of waves from two coherent sources. What is the meaning of coherent sources ? [1mark]
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ii)
Describe the movement of two similar ships that are located at A and B. Explain your answer. [4mark]
d) A new harbour is to be built at a new location. The suggested new location is either at a bay or a cape. Four models for the structure of the retaining wall are given. Table below shows the location and the characteristics of the four retaining walls. Explain the best location and the suitability of each characteristic in Table above. Determine the most suitable retaining wall to be used. [10marks]
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2.
Diagrams 4.1 and 4.2 show two taps relesing droplets of water into large containers. The number of droplets which fall per second in Diagram 4.1 is more compared to the number of droplets in Diagram 4.2. The cross sections of the water waves formed from the droplets in the containers are shown in the diagrams.
Based on the above information and observation : (a)
State one suitable inference
[1 mark]
(b)
State one suitable hypothesis
[1 mark]
(c)
With the use of apparatus such as a ripple tank , a vibration motor with adjustable frequency and other apparatus describe an experiment framework to investigate the hypothesis stated in 4 b). In your description, state clearly the following: (i) (ii) (iii) (iv) (v) (vi) (vii)
Aim of the experiment Variables in the experiment List of apparatus and materials Arrangement of the apparatus The procedure of the experiment which include the method of controlling the manipulated variable and the method of measuring the responding variable. The way you would tabulate the data The way you would analyze the data [10 marks]
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3.
Figure 1and 2 show the interference patterns produced by two vibrators vibrating on the surface of water in a ripple tank.
(a) What is meant by interference? (b) Based on the figures above, compare the patterns of interference of the water waves. State the relationship between the distance between the vibrators and the distance between two consecutive nodal and antinodal lines. (c) Draw a labelled diagram to show the interference pattern produced by two coherent light sources. (d) With the help of ultrasonic waves, a fishing boat can detects shoal of fish in the sea. (i) (ii)
What is ultrasonic wave? Explain how fishing boats detect shoal of fish in the sea using ultrasonic waves.
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4.
(a) The picture below shows the different types of mobile phones available. The operation of the mobile phones needs a certain type of wave for transmitting and receiving signals.
The table below shows the characteristics of four types of waves. Electromagnetic Type of waves waves P Sound Q Infrared rays R Microwaves S Gamma rays (i) (ii)
Speed ( m s-1) 300 3.0 x 108 3.0 x 108 3.0 x 108
Effect to user Not harmful Not harmful Not harmful Harmful
Sources of waves Vibrating obbects Hot object Electric current Sun
What is the relationship between wavelength and frequency? You are assigned to study the characteristics of waves in the table to be used in a mobile phone. From the table, explain the suitability of each characteristic and hence determine which wave is most suitable to be used as a wave for telecommunication. Give reasons for your choice.
(b) List 3 differences between sound waves and radio waves. (c) A radar at the control tower in an airport transmits and receives signals in an interval of 4.0 ms. (The speed of radar is 3.0 x 108 m s-1). (i) (ii)
Name the phenomenon used in determining the position of an aircraft. Determine the distance of the plane from the control tower.
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5.
The figure below shows an electric kettle connected to a 240V power supply by a flexible cable. The kettle is rated “240V, 2500W”.
The table below shows the maximum electric current that is able to flow through wires of various diameters. Diameter of wire / mm 0.80 1.00 1.20 1.40
Maximum current / A 8 10 13 15
(a) What is the current flowing through the cable when the kettle is switched on? (b) Referring to the table above, (i) (ii)
what is the smallest diameter wire that can be safely used for this kettle? explain why it is dangerous to use a wire thinner than the one selected in (b)(i)?
(c) State one precautionary measure that should be taken to ensure safe usage of the kettle. (d) Mention one fault that might happen in the cable that will cause the fuse in the plug to melt.
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6.
Anthony records the detail of the electricity usage of the various electrical appliances in his house for a day. The observations are shown in the table below. Electrical Appliances Air conditioner Water heater Lights Kettle Home theatre
Power rating / W 2.0 3.0 0.8 2.0 1.0
Duration switched on / hr Energy usage / kWh 3.0 0.3 10.0 0.2 2.0
(a) Complete the table above by filling in the energy usage for the various appliances. (b) Which appliance cost the most to use? (c) If the meter that records the daily electrical energy usage is 2564.2 kWh at the beginning of the day, what will be the reading at the end of the day? (d) The wires connected to the water heater is thicker than those connecting to the lights. Give a reason for this.
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7.
Figure 1 shows the reading of the voltmeter in a simple electric circuit. Figure 2 shows the reading of the same voltmeter.
(a) What is meant by electromotive force (e.m.f.) of a battery? (b) Referring to Figure 1 and Figure 2, compare the state of the switch, S, and the readings of the voltmeter. State a reason for the observation on the readings of the voltmeter. (c) Draw a suitable simple electric circuit and a suitable graph, briefly explain how the e.m.f. and the quantity in your reason in (b) can be obtained. (d)
The figure above shows a dry cell operated torchlight with metal casing. (i) (ii) (iii)
8.
What is the purpose of the spring in the torchlight? Why is it safe to use the torchlight although the casing is made of metal? What is the purpose of having a concave reflector in the torchlight?
A group of engineers were entrusted to choose a suitable cable to be used as the transmitting cable for a long distance electrical transmission through National Grid Network.
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Four different cables and their characteristics of the cables were given. The length and diameter of all the cables are similar. (a) Define the resistance of a conductor. (b) The table below shows the characteristics of the four cables, A, B, C and D. Resistivity /Wm 0.020 0.056 0.031 0.085
A B C D
Maximum load before breaking / N 500 300 400 200
Density / kgm-3
Rate of expansion
2800 3200 5600 3800
Low Low Medium High
Base on the above table: (i) (ii)
Explain the suitability of each characteristic of the cable to be used for a long distance electricity transmission. Determine the most suitable wire and state the reason.
(c) Suggest how three similar bulbs are arranged effectively in a domestic circuit. Draw a diagram to explain your answer. Give two reasons for the arrangement. (d) An electric kettle is rated 2.0 kW. (i) (ii)
9.
Calculate how long would it take to boil 1.5 kg of water from an initial temperature of 28oC. [specific heat capacity of water = 4200 J kg-1 oC-1] What is the assumption made in the calculations above?
Figure 16 and Figure 18 show photographs of two circuit. Each circuit contains four identical bulbs connected to four identical new dry cells.
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(a) (i) State the energy transformation that take place in the bulb (ii) Draw a circuit diagram for each photograph.
Figure 16
[ 1 mark] [ 3 marks]
Figure 17
(b) (i) Observe the photographs in Figure 16 and Figure 17. Compare the brightness of the bulbs. Relate the brightness of the bulbs between Figure 16 and Figure 17 to deduce a concept in physics with regard to the potential difference and the current flow for the bulbs in series and parallel circuits. [6 marks] (c ) Figure 18 shows a model of an incubator used to hatch eggs. The temperature in the incubator must be maintained around 39 ° C. Every part of the eggs must receive uniform heat. The eggs are hatched in about 20 days.
Using an appropriate concept in physics , explain the modification required to the above incubator so as to efficiently hatch about 200 eggs. [10 marks]
10.
Figure 1 and Figure 2 below show the structures of a d.c motor and a d.c. generator respectively.
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(a) (i) (ii)
State the change of energy that occurs in a motor. Sketch the catapult field that is produced in Figure 1 above.
(b) Referring to the figures above, state two differences between the two motors. (c) Using suitable physics concept, describe what must be done to increase the efficiency of the d.c. motor.
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11.
The diagram above shows the structure of a simple transformer. (a) (i) (ii)
What is the meaning of 'electromagnetic induction'? List down two differences between a step-up and a step-down transformer.
(b) the core of a transformer plays an important part in determining the efficiency of the transformer. The table below shows four different metals P, Q, R and S together with several characteristics associated with them. Metals P Q R S
Density / kg m-3 Resistivity / Ω m 8930 6500 10750 7120
5.0 x 10-8 3.0 x 10-8 4.0 x 10-8 3.0 x 10-8
Easily oxidized No No Yes Yes
Easily magnetized / demagnetized Yes Yes No No
Explain the suitability of each of the characteristics mentioned in choosing a smelt to be used as the core of a transformer. Finally, which metal would you choose to be used and why? (c) The diagram below shows a transformer with four output terminals. The primary coil consists of 200 turns connected to a 6V a.c. supply. The number of turns between the terminals of the secondary coils are as shown below.
(i)
(ii) 12.
Calculate the output voltage between the terminals (a) PQ (b) PR (c) QS (d) RS If you were to connect a bulb labelled “14W, 12V”, to which pairs of terminals would you connect the bulb to?
Figure 1 shows an electric circuit with one diode and the trace produced as shown on a CRO connected across the resistor R. Figure 2 shows an electric circuit with four diodes and the trace produced as shown on a CRO connected across the resistor R.
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(a) What is meant by rectification? (b) Based on the figures above, compare the arrangement of the diodes, the type input voltage and the type output voltage. State the use of the diodes in the figures above. (c) Trace the path taken by the current in Fig.2 if the terminal X is positive. (d) Name an electric component that needs to be connected to the output of both the circuits to produce a more constant output. (e) Sketch a graph to show the effect on the output voltage of putting a capacitor in the circuit in Fig.1.
13.
The diagrams below show four different circuits A, B, C and D consisting various electrical components including a transistor, T.
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(a) What is the meaning of semiconductor material? (b) State briefly how is a p-type semiconductor produced? (c) You are to set up a transistor circuit which can be used as a fire alarm. Referring to the circuits A, B, C and D, discuss the suitability of the type and location of various components in the making of the fire alarm. Hence, choose the circuit which is suitable to be the circuit used in fire alarm. (d) The transistor circuit below functions as a fire alarm. The alarm will sound if the potential difference across R1 is greater than 1.0 V.
If the resistance of R1 and R3 are 500 Ω and 1000 Ω respectively, (i) calculate the potential difference across R 3, (ii) calculate the potential difference across R 1, (iii) will the alarm be turned on? Give a reason for your answer.
14.
(a) Equation 1 shows the decay of Radon-222. Equation 2 shows the decay of Uranium-238 218 Equation 1 : 222 86 Rn → 84 Po + X
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234 Equation 2 : 238 92 U → 90Th + Y
(i) (ii)
What is meant by the term 'radioactivity'?. Based on the two equations above, state two similarities in the decays. From the two equations determine the particles represented by X and Y.
(b) In the explosion of an atomic bomb, a mass defect of 0.1 g occurred in 1μs. This mass is changed into energy. Determine how much energy is produced. (c) The photograph below shows a nuclear power station. What are the safety precautions that must be taken in a nuclear power station.
15.. Radioactive isotopes are widely used in various industries. Among them is as a tracer to detect the
location of leaks in an underground water pipes. The table below shows the characteristics of four types of radioisotopes U, V , W and X.
U V W
Solubility in water Soluble Soluble Insoluble
Half-life 1 month 2 weeks 1 month
Type of radiation emitted α-particles β-particles α-particles
Penetrating power Low Moderate Low
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X
Insoluble
(a) (i) (ii)
2 months
β-particles
Moderate
What are isotopes? On the same axes, sketch two graphs showing the changes in the activities of radioisotopes W and X. Assume that the activities of both radioisotopes are the same in the beginning. Label the graphs appropriately.
(b) The Local Water Board involved in the supply of water to the residents of Harmony Garden noticed a drop in the pressure of one of the pipes indicating a leak somewhere. Referring to the table above, discuss the suitability of each characteristics of the radioisotopes that can be used as a tracer to detect the location of the leak. Which isotope is the most suitable to be used and why? (c) The table below shows the activity of a sample of a radioactive substance. Activity (i) (ii)
16.
880
960
980
820
Calculate the average activity of the radioactive substance. If the half-life of the radioactive substance is 5 hours, what would you expect the activity be 10 hours later?
The figure below shows a simple transformer.
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(a) What happens to the core when the switch is turned on? (b) When the switch is turned off, state what happens (i) (ii)
in the coil RS and the pointer of the galvanometer.
(c) If the galvanometer is replaced with a bulb with rating “30V, 42W”, it is found that the bulb lights up normally when PQ is connected to a power supply of 240V a.c. Calculate the ratio of the number of turns in the coil PQ to the number of turns in the coil RS. (d) In practice, a transformer is never ideal. Give two reasons for the fact that a transformer can never be 100% efficient.
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17.
The diagram above shows the various components found in an electric bell. (a) State the principal based on which the electric bell operates? (b) When the switch is pressed, (i) What happens to the soft iron core? (ii) State the polarity of the end X. (iii) What happens to the hammer? (c) What happens when the soft iron core is replaced with steel? (d) Name another device that uses the principle of electromagnetism in its operation.
18.
The diagram below shows three transformers K, L and M connected to a 240V a.c. power supply. Their outputs are connected to 3 bulbs which are arranged differently.
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(a) All the three transformers are identical. Calculate the output voltage of the transformers. (b) When turned on, a current of magnitude of 0.25 A flows in the primary coil and all the bulbs lighted up with normal brightness. (i) (ii) (iii) (iv) (v)
19.
What is the input power of the transformers? Determine the output power for each of the transformers. Calculate the efficiencies of each transformer. Is any of the transformers ideal? Give a reason for your answer. Suggest one way to increase the efficiency of a transformer.
The figure below shows the structure of a simple d.c. generator. The coil in the generator is rotated about the axis in the direction shown.
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(a) What are the names of the parts labelled X and Y? (b) (i) (ii)
In the figure above, show the direction of the forces that act on the sides AB and CD of the foil. What is the rule that is used to determine the direction of the force that acts on the coil?
(c) The graph below shows how the induced e.m.f. produced by the generator above varies with time.
Sketch a graph showing the variation of the induced e.m.f. produced if the coil is rotated at a faster rate. (d) What change is required to be made to the structure above if it was to be used as an a.c. generator?
20.
Figure 1 shows a vertical wire carrying an electric current in the direction shown. Figure 2 shows the bird's-eye view of the wire.
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(a) On Figure 2, (i) (ii)
draw the pattern of the magnetic field formed around the wire. draw an arrow on the plotting compass C to show the direction of the magnetic field through the compass.
(b) State the effect on the pointer in the compass if (i) (ii)
a current of bigger magnitude flows through the wire in the same direction as in Figure 1. the direction of the current is reversed.
(c) Compare the strength of the magnetic field at point X and point Y in Figure 1. 18.
A length of flexible copper wire fixed at two points P and Q is held vertically such that a portion of it is in between the poles of a horseshoe magnet as shown in Figure1 below.
(a) (i) (ii)
Figure 2 shows the side view of the arrangement as seen from the observer. In Figure 2, draw what the wire might look like if a strong electric current flows along the wire from P to Q. Give an explanation to your answer in (a)(i).
(b) What is the rule you use to determine your answer in (a)(i)?
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(c) Give two changes that could be made so that the copper wire will act in the direction to your answer in (a)(i). 21.
The diagram shows the structure of a simple CRO.
(a) Name the components labelled P, Q, R, S and T. (b) Explain what is meant by 'thermionic emission'. (c) The figure below shows a trace formed on the screen of a CRO.
The time base is set at 5 ms/cm. (i) What is the period of the signal applied to the CRO? (ii) Hence, what is the frequency of the signal? (iii) If the same signal is applied to the CRO but the time base is readjusted to 10 ms/cm, draw a sketch to show the trace that will now be formed on the screen?
22.
The diagram below shows a circuit which acts as an automatic switch to turn on the motor M when the surroundings is dark.
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(a) Name the component labelled (i) P (ii) Q (iii) S (b) What is the function of the component labelled R? (c) In the figure above, show how the collector current, I c and the base current, Ib might flow. (d) What happens to the magnitude of the potential difference V H when the surroundings become bright? (e) Explain how the change in the potential difference, V H, will cause the motor M be turned on?
23.
The figure below shows a circuit consisting three different logic gates.
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(a) Name the logic gates (i) P (ii) Q and (iii) R (b) Complete the truth table for the system shown above. Input A 0 0 1 1 (c) (i) (ii)
24.
Output B 0 1 0 1
The combination of the logic gates above can be replaced by a single logic gate. What is this equivalent logic gate? Give the Boolean equation for the logic gate in your answer in ( c)(i) above.
The circuit below shows a logic circuit used in a cold room where frozen meat is stored. The alarm will be turned on if the temperature of the cold room is too high. The buzzer will be turned OFF if the output logic is 0 and be turned ON if the output logic is 1.
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(a) Name the logic gate used in the circuit above. (b) Based on the information above, complete the truth table for the logic gate above. Input
Output
Alarm OFF ON
(c) Name the component labelled E. (d) If the temperature of the cold room increases, what happens to the quantity in the table below? Complete the table with the appropriate answers. Resistance of E Current flowing through the logic gate Condition of the alarm
25.
The diagram below shows the circuit of a transistorized radio receiver.
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(a) Name the components labelled A, B and C. (b) The component D is a transistor. What type of transistor is it? (c) State the change in energy that occurs in the component labelled C. (d) Sketch the shape of the signals that (i) (ii)
flows into B, flows into the transistor D.
(e) What is the function of the transistor in the circuit above? 24.
Below are some data about a CRO in use : Voltage across heating filament = 6.0 V Potential difference across cathode and anode = 2 x 10 3 V Heating current = 0.5 A Electron beam current = 2 mA (a) Place a tick (
) on the type of power supply that can be applied across the filament.
d.c voltage a.c voltage (b) State two uses of C.R.O in the school laboratory. (c) Why does the electron beam get deflected by in magnetic field? (d) Calculate the velocity of the electron beam as it leaves the anode? (e / m for electron is 1.76 x 1011 C kg-1) (e) Determine the number of electrons which move through C.R.O in 10 minutes. (e =1.60 x 10 -19 C) 26.
73 32 X represents the nucleus of an atom X.
(a) What is meant by (i) (ii)
proton number and nucleon number of an atom
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(b) How many protons and neutrons are there in the nucleus of X? (c) If this nucleus is unstable and emits α-particles to become a more stable atom Y, write down the equation for this decay. (d) The half-life of this nuclide is 10 days. A laboratory has an initial mass of 250 g of a sample of this radioactive material. (i) (ii)
27.
How much of this material remains after 30 days? State one safety precaution that should be taken when handling this material.
The diagram below shows the penetrating powers of three radioactive radiations X , Y and Z.
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(a) Arrange, in increasing order, the penetrating powers of these radiations. (b) In the diagram below, draw the path taken by these radiations when they travel into an area where the direction of the magnetic field is directed into the paper.
(c) What happens to the proton number and the nucleon number if a radioactive nuclide were to emit radiation X? (d) Among the three radiations, state two properties of radiation Z.
28.
(a) Complete the statement below by inserting a word of phrase in the blanks provided. In the Rutherford experiment, ____________ charged α-particles were projected towards a ____________ gold foil. Most of the particles were not deviated showing that the gold foil is
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mostly __________ . A few particles were deviated through a small angle or even got deflected. It can be concluded from this experiment that the nucleus has a relatively large ___________ and a __________ charge. (b) The table below shows three characteristics of three types of radiations emitted from radioactive materials. Complete the table with the correct information. Types of radiations α-particles β-particles γ-rays
30.
Nature
Charge
Proton number
Nucleon number
A smoke detector contains a radioactive source which is a α-particles emitter.
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The diagram above shows the structure of the smoke detector. The ammeter shows bigger reading when there in no smoke in between the plates compared to when there is smoke. (a) State the nature of α-particles. (b) Explain the presence of electric current flowing in the circuit. (c) Explain why β-particles emitters are not used in this detector. (d) Americium-241 is an α-particle emitter and is represented by the symbol 241 Am . It decays into 95 Neptunium 237. The symbol for neptunium is Np. Write down the equation that represents the decay of Americium-241.
32.
An experiment is conducted to detect the number of radioactive particles emitted by a radioactive source by a group of students. The diagram below shows the set-up of the apparatus.
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(a) What is the name of the detector used in the experiment? (b) The students measures the number of particles emitted by three different radioactive substances X, Y and Z in a period of 1 minute. The experiments were repeated every hour. The results are shown in the table below Time/hr 0 1 2 3 4
Source X 2400 1200 600 300 150
Number of particles detected / minute Source Y Source Z 3600 7200 2600 5200 1800 4400 1000 3600 300 3100
Arrange the radioactive source in order of ascending half-life. (c) (i) (ii)
32.
What is the half-life of the radioactive source Y? Determine the time taken for the radioactive source Y to decay to 6.25% of its original mass.
The radioactive isotope of radon is radon-220, represented by the symbol 220 86 Rn . Radon-220 is an αparticle emitter and decays into Polonium ( symbol Po). (a) The number 220 for radon is called the …………………….
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(b) What is the number of neutrons in the nucleus of radon-220? (c) The nuclear equation that represents the decay of radon-220 is 220 x 86 Rn → y α
+ 116z Po
What is the number represented by (i) x (ii) y (iii) z (d) During the decay of radon-220, there is an apparent loss of mass of 1.14 x 10 -29 kg. (i) (ii)
Write down the equation that enables the amount of energy released to be determine. Calculate the amount of energy released.
10. Diagram 10.1 and Diagram 10.2 show wire coils connected to the ammeters switches and d. c power supply.
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When the switch is on and iron filings of the same amount is spread on each of the cardboard surface, the pattern of the iron filings is formed as shown in the diagrams. (a) What is meant by magnetic field ? [1 mark] (b) Using Diagram 10.1 and Diagram 10.2 , compare the number of turns of the coils, the pattern of the iron filings and angle of deflection of the ammeter indicator. [ 3 marks] (c) State the relationship between the strength of the magnetic field and (i) the pattern of the iron filings (ii) the number of turn of the coil
[2 marks]
(d) Diagram 10.3 shows two thin copper strips , PQ and RS , connected to a circuit.
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Explain what happens to PQ and RS , when the switch is on.
[ 4 marks]
(e) Diagram 10.4 shows an electric motor which is supplied with a 12 V a.c
(i) (ii)
Explain how the motor is able to rotate Using a 12 V a.c power supply , explain the modification that needs to be done on the motor and the external circuit to enable the motor to be a d.c electric motor and rotate faster. [10 marks]
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11. Figure 4.1 shows circuits J,K , L, M and N each containing an ideal transformer. Diodes in the circuits are used for the purpose of rectification.
(i) (ii) (iii)
What is meant by rectification ? [1 mark] Explain the working principle of a transformer. [4 marks] You are asked to make a 12 V battery charger. Study the circuits , J ,K,L , M and N in Figure 4.1 and consider the following aspects : - type of transformer - ratio of number or turns in primary coil to secondary coil - type of rectification - characteristic of output current. [10 marks]
Explain the suitability of the above aspects and hence determine the most suitable circuit to make the battery charger. Justify your choice. [10 marks]
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(b) Figure 4.2 shows a circuit consisting of a transformer , an ammeter and two light bulbs. The ammeter reading is 0.5 A and both light bulbs light up with normal brightness.
(i) (ii)
What is the output of the transformer ? Calculate the efficiency of the transformer ?
[5 marks]
6. Most of our electrical energy comes from hydroelectric power stations and thermal power stations. These power stations are connected by cables to transmit electricity to users in industries , offices , schools and houses. This system is called the national grid network. (a) (i) State the transformations of energy in a hydroelectric power stations. [ 1 mark] (ii) Explain briefly the importance of the national grid network system in distributing electrical energy to the users. [ 4 marks] Figure 12.1 shows how a model of an electric transmission system can be set up in laboratory. The model consists of a power station that generates 12 V of alternating current ( a.c) that transmits the electrical energy to the users using transmission wires and transformers P ,Q and R.
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You are required to set up a model as in Figure 12.1 using the information in Table 12.1
Number of turns of the coil 1200 1000 500 400 160 120
Type of transformer core Solid copper core Laminated copper core Solid soft iron core Laminated soft iron core
Materials of transmission wire Constantan Copper Aluminium Nochrome
(b) Using the information in Figure 12.1 and Table 12.1 determine : (i) the numbers of turns in the primary and the secondary coil of transformers P, Q and R and show your working, (ii) the type of core you will use in all the transformers and justify your choice, (iii the material you will use for the transmission wire and justify your choice. [10 marks] (c) If the resistance of the transmission wires between transformers P and Q in the model at is 30 Ω , calculate : (i) (ii)
the current that flows in the transmission wire, the power loss due to the heating effect of the current in the transmission wire [ 5 marks]
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7. Diagram 10.1 and Diagram 10.2 show two electrical circuits containing semiconductor diodes.
(a) (b)
What is meant by a semiconductor ? [1 mark] Using diagram 10.1 and Diagram 10.2, relate the lighting of the bulbs, the current and the way the diode is connected to the terminals of the battery to deduce a relevant physics concept. [5 marks]
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(c)
Diagram 10.3 shows a full wave rectifier circuit.
(i) (ii)
(d)
Draw the wave form of a full wave rectification. A capacitor is placed across the output to smooth the current. Draw the wave form produced. Explain how a capacitors is used to smooth the current.
[1 mark] [3 mark]
Diagram 10.4 shows a circuit a transistor that acts as an automatic switch.
The transistor in the circuit causes the light emitting diode (LED) to light up when it is dark. A technician wants a fan labeled 240V, 100W in a room to be automatically switched on when the room is hot.. Suggest modifications that can be made to the circuit in Diagram 10.4 so that the fan can be automatically switched on when the room is hot. Draw the modified circuit. State and explain the modifications based on the following aspects : the electrical components that are needed to replace the LED and the light dependent resistor (LDR) in the circuit. the positions of the electrical components in the circuit. [10 mark]
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8.
Production of nuclear energy and detecting the volume of a material are two examples of the use of radioactive materials in industry. Table 2.1 shows an equation of a reaction and total atomic mass before and after a nuclear fission. Nuclear fission Before reaction Equation Total atomic mass
239 94
1 0
Pu +
n
After reaction 145 56
Ba +
240.06082 a.m.u
93 38
Sr + 2
1 0
n + Energy
239.85830 a.m.u
TABLE 2.1 Table 2.2 shows an equation of a reaction and total atomic mass before and after a nuclear fusion. Nuclear fusion Before reaction Equation Total atomic mass
2 1
H +
3 1
H
After reaction 4 2
He +
5.03013 a.m.u
1 0
n + Energy
5.01043 a.m.u TABLE 2.2
(a)
(i) What is meant by a nuclear fission? [ 1 mark] (ii) Using only the information given in Table 2.1 and 2.2, compare nuclear fission and nuclear fusion. Hence state the relationship between mass and energy evolved. [ 5 marks]
(b)
Nuclear fission produces a chain reaction. Describe how the chain reaction happens in a nuclear fission of an atom uranium. [ 4 marks]
(c) A paint-producing factory wants to develop a volume control system which can ensure the quantity of paint in every tin is within a specific range. The tins of paint are transported on a conveyor belt as shown in Figure 2.1. If the volume of the paint is less or more than the specific range of volume, the tin will be separated automatically.
FIGURE 2.1
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Using your knowledge on radioactivity and Figure 2.1, explain; (i) the radioactivity material and equipment required to develop the volume control system, (ii) how the equipment is assembled, (iii) how the system works. [10 marks] 9 . Diagram 10.1 and Diagram 10.2 show the deflection of a radioactive emission in an electric field.
(a) What is the meaning of radioactivity?
[1 mark]
(b) Using Diagram 10.1 and Diagram 10.2, (i) state the charge of the radioactive emission, [1 mark] (ii) compare the voltage of the EHT and the deflection of the radioactive emission. [2 marks] (c) State the relationship between (i) the voltage of the EHT and the strength of the electric field between the plates, [1 mark] (ii) the strength of the electric field between the plates and the deflection of the radioactive emission. [1 mark]
(d) Diagram 10.3 shows a type of nuclear reaction.
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DIAGRAM 10.3 (i) Name this type of nuclear reaction. [1 mark] (ii) Explain how nuclear energy is produced from the nuclear reaction shown in Diagram 10.3 [3 marks] (e) Diagram 10.4 shows how a radioactive source is handled by a student.
(i) (ii) (iii)
The method shown is not safe. Suggest and explain: The equipment to be used in handling a radioactive source. Modifications to the storing method to ensure safe keeping of the radioactive source. Other precautions that need to be taken when handling a radioactive source. [10 marks]
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