Year 11 GCSE PHYSICS REVISION QUESTIONS PAPER 1. Higher Level. Energy and Electricity

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1 Year 11 GCSE PHYSICS REVISION QUESTIONS PAPER 1 Higher Level Energy and Electricity Moulsham High School 1

2 1. A domestic electricity bill for the Smith family is shown. The unit of electricity is the kilowatt hour (kw h). Charges for electricity used from 15 May 1998 to 11 August 1998 Domestic Economy 7 Present reading Previous reading Units used Pence per unit Charge amount Day Night Standing charge 5.0% Total charges this period (a) Use the information to calculate: (i) the cost of the electrical energy used during the night; the total amount to be paid. The Smiths use a tumble dryer every day to dry their washing. Mrs Smith decides to use the dryer only at night. Suggest why this is a sensible idea (c) The diagram represents an electrical circuit containing a motor, a variable resistor and a power supply. power supply M slide control variable resistor Moulsham High School 2

3 (i) Describe how to use the variable resistor to reduce the speed of the motor. Explain why the motor slows down. (Total 7 marks) 2. There are three conductors in the flexible cable that connects an iron to the mains electricity supply. These conductors are called earth, neutral and live. (a) Which of these (i) supplies energy to the iron?. is covered with blue insulation?. (iii) acts with the fuse to prevent electrocution?. The diagram shows the live and neutral connections to the element in an iron. live element neutral Moulsham High School 3

4 (i) When a current passes in the element, what happens to the energy supplied to the iron?. In normal use, the current in the element is 7 A. Which two of these fuses would allow this current to pass? 1A 3A 5A 10A 13A (iii) Use words from the box to complete the sentences. high low melt quickly slowly solidify If the fuse has a rating which is too low, the current will cause the fuse wire to..., breaking the circuit. If the fuse has a rating which is too high, the fuse wire will not break the circuit... enough when a fault occurs. (Total 7 marks) 3. Electricity passes into a substation at V through overhead cables. It passes out of the substation at V through underground cables. electricity in ( V) substation electricity ( V) out (a) What device is used to change the size of the voltage? Moulsham High School 4

5 Suggest one advantage and one disadvantage of using overhead cables for the high voltage electricity that passes into the substation. Advantage Disadvantage (c) Suggest one advantage and one disadvantage of using underground cables in areas where people live and work. Advantage Disadvantage (d) In the future more of our electricity will be generated using wind turbines built at sea, near the coast. Explain why it is better to build these wind turbines at sea rather than on land. (Total 8 marks) Moulsham High School 5

6 4. (a) The diagram shows how electricity passes from a power station generator to homes. generator transformer A transformer B homes (i) Describe how electricity is generated in the generator What is the purpose of transformer A?... (iii) Why is transformer B needed?... The diagrams compare the energy flow through two types of power station. gas fired coal fired 50 J wasted 60 J wasted 100 J from gas 100 J from coal 50 J as electricity 40 J as electricity (i) What happens to the energy wasted in the power stations?... Give one advantage of burning gas rather than coal.... (Total 6 marks) Moulsham High School 6

7 5. A technician wishes to find the resistance of a lamp for an overhead projector. He measures the current and voltage in an electrical circuit which includes the lamp. The electrical symbol for the lamp is (a) Draw a circuit diagram to show how he finds the resistance of the lamp. Label any devices used in your circuit. The lamp in an overhead projector is protected by a thermistor. The graph shows how the resistance of the thermistor changes with temperature. Resistance in ohms Temperature in ºC Moulsham High School 7

8 The thermistor and the lamp are connected in series. (i) Describe how the thermistor protects the lamp when the projector is first switched on. What happens as the projector lamp warms up? (iii) What is the resistance of the thermistor at 20 C? (iv) The resistance of the lamp is 300 Ω at 20 C. In a series circuit: Total Resistance R = R 1 + R 2 Calculate the current in the circuit at 20 C when the projector is operated at 240 volts. (Total 10 marks) Moulsham High School 8

9 6. Andy mows his lawn with a mains powered electric lawnmower. cable There is no earth wire in the cable connected to the mower. However, the mower is safe to use because it is double insulated. (a) Explain how the double insulation protects the user. To increase safety, the manufacturer recommends the use of a residual current circuit breaker (RCCB), when using the mower. (i) How does the RCCB protect the user if the cable is damaged? Suggest an advantage of using a RCCB rather than a fuse.... (Total 5 marks) Moulsham High School 9

10 7. Kate makes a simple alarm circuit using a light dependent resistor (LDR) and a buzzer. 6 V (a) (i) Explain why the buzzer sounds when light shines on the LDR In bright light, the total resistance of the buzzer and the LDR is 400 ohms. What is the current in the circuit? Kate makes another circuit which includes a variable resistor. A V (I) (i) Describe how the brightness of the lamp changes as the resistance of the variable resistor increases She draws a graph for different values of the voltage and the corresponding current. Moulsham High School 10

11 voltage in V current in A Explain the shape of the graph. (Total 7 marks) 8. (a) Nuclear power stations produce waste. Explain why the disposal of this waste is a problem. Moulsham High School 11

12 Describe the advantages of generating electricity using nuclear power, rather than other methods. (Total 6 marks) 9. The diagram shows the lighting circuit in an office. live fuse (5A) 230V neutral (a) (i) Explain why the lamps are connected in parallel rather than in series. What does the fuse protect? (iii) Explain how a fuse works. Moulsham High School 12

13 A label on a computer used in the office includes the following information. 230 V a.c kw Electrical energy costs 8p per kilowatt hour (kw h). Use the equation cost = power (kw) time (h) cost of 1 kw h to calculate how much it costs to use the computer for 30 minutes. (c) Calculate the resistance of the computer when the current is 0.9 amps. (Total 10 marks) 10. Wind farms are groups of wind driven generators. The wind turns the blades attached to the generator. Moulsham High School 13

14 Explain how the motion of the blades enables a generator to produce electricity (Total 4 marks) 11. Tim grows plants in a greenhouse. (a) He decides to try to increase their rate of growth by using artificial light. Tim has a choice of light bulbs. a filament bulb a compact fluorescent bulb (CFL) The two lamps shown in the table produce the same amount of light. type of bulb power (watts) cost of bulb ( ) filament CFL Use the information in the table to help you to explain why Tim decided to use compact fluorescent lamps, even though they cost more to buy. To reduce the cost of heating the greenhouse, Tim fits bubble wrap on the inside Moulsham High School 14

15 of the glass. Explain how fitting the bubble wrap reduces the cost of heating the greenhouse. (Total 5 marks) 12. The current in a wire was measured at different voltages. The table shows the results. Current in amperes (A) Voltage in volts (V) Moulsham High School 15

16 (a) Use the data to draw a graph of current against voltage. 1.0 Current in A Voltage in V Describe how the current in the wire changes when the voltage is increased. (c) Calculate the resistance of the wire when the current is 0.6 A. (Total 8 marks) 13. The graph shows how the current in a thermistor depends on its temperature. Moulsham High School 16

17 current in A temperature in C (a) What is the current in the thermistor at a temperature of 37 C?... The thermistor is connected to a 2.5 V d.c. supply. Calculate the resistance of the thermistor at 37 C..... (c) Use the graph to explain how the resistance of the thermistor changes when its temperature increases. Moulsham High School 17

18 (d) A thermistor is used to keep the temperature of an incubator at 37 C. If a large current passes in the thermistor, it switches the incubator heater off at a temperature below 37 C. Suggest how this happens.... (Total 8 marks) 14. (a) The diagram shows a diode connected in series with a resistor and an a.c. supply. (i) voltage The graph on the left shows how voltage across the diode changes with time. current 0 0 time time Draw a graph that shows how the current in the diode changes with time. Use the grid on the right. The connections to the diode are now reversed. Draw a graph that shows how the current in the diode changes with time. Use the grid below. current 0 time The graph below shows how the current in a diode depends on the voltage across it. Moulsham High School 18

19 current in A voltage in V (i) What current passes in the diode when the voltage across it is +0.7 V?... Calculate the resistance of the diode when the voltage across it is +0.7 V (iii) Describe how the resistance of the diode changes as the voltage across it is increased from 0 V to +0.8 V (Total 9 marks) Moulsham High School 19