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Question 1
This question is about mains electricity in the UK. The UK mains supply is an A.C. supply. |
a) | Describe what an A.C. supply is.
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b) | In UK plugs, the live wire is A blue B brown C green and yellow stripe D random
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c) | The neutral wire is A blue B brown C green and yellow stripe D random
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c) | The Earth wire is A blue B brown C green and yellow stripe D random
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d) | Which wire should the fuse be connected to? A live B earth C neutral
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Question 2
a) | A kettle is rated a 2 kW, 230 V. Calculate the operating current. Give your answer to 1 decimal place.
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b) | A student has 3 A, 10 A and 13 A fuses. The student fits a 3 A fuse to the kettle and turns it on. Explain why the kettle won't work with a 3 A fuse fitted.
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c) | State which fuse the student should have fitted to the kettle and explain why.
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d) | The metal case of the kettle is connected to the earth wire. Explain why metal appliances need to be earthed.
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Question 3
An electric oven has a heating element and a fan. The table below shows the operating conditions for the heating element and the fan. |
a) | Calculate the current flowing through the fan.
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b) | The student needs to replace the fuse in the oven. She has 3A, 5A and 13A fuses. Calculate the total current requirement and suggest which fuse the student should use.
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c) | A fault occurs in the oven and the live wire touches the metal case of the oven. Explain how the safety features of the plug work to prevent the user getting a dangerous electric shock.
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Question 4
a) | A fridge has a power rating of 800 W. Calculate the energy required to run the fridge for 1 day.
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b) | The fridge operates of the UK mains supply. State the operating voltage and frequency of the UK mains supply.
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c) | Calculate the operating current of the fridge.
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d) | Which fuse should be fitted to the fridge? A 3 A B 5 A C 10 A D 13 A
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Question 5
A homeowner needs to replace the heating element in their electric oven. The table below summarises the details of 3 different heating elements. |
a) | Calculate the power of heating element B. Give your answer to 3 significant figures.
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b) | The oven is fitted with a 3 A fuse. Which heating element should the homeowner avoid using?
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c) | The oven is turned on for 40 minutes. Calculate how much extra energy heating element B uses compared to heating element A.
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d) | Both heating elements A and B are capable of heating the oven. Explain heating element should the homeowner install.
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Question 6
This question is about the wiring of UK mains electricity plugs. |
a) | State the name and purpose of part E.
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b) | State the name of the three wires A, B and C. Describe the purpose of the three wires A, B and C.
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c) | A fuse is a safety device used to prevent dangerously high currents flowing. Explain how a fuse works to keep electrical circuits safe.
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d) | Circuit breakers are another common safety device used to cut off circuits in the event of an electrical fault. Describe the advantages and disadvantages of using circuit breakers and fuses.
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Question 7
a) | This question is about an electric hairdryer. The hairdryer contains a heating element, an electric fan and a plastic case. The hairdryer runs off the UK mains supply. State the voltage and frequency of the UK mains supply.
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b) | The hairdryer is not earthed. Explain why the hairdryer is still safe to use despite not being earthed.
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c) | The power of the hairdryer is 1.2 kW. Explain what is meant by 1.2 kW.
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d) | Calculate the energy transferred in 10 minutes of operation.
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Question 8
This question is about a coffee machine. |
a) | The heating element of the coffee machine is rated at 1,500 W, 230 V. Calculate the resistance of the heating element. Give your answer to 1 decimal place.
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b) | Calculate the current flowing through the heating element. Give your answer to 2 decimal places.
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c) | A fault develops in the coffee machine and the live wire touches the metal casing. Explain how earthing and a fuse prevent the user from getting an electric shock.
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c) | A fault develops in the coffee machine and the live wire touches the metal casing. Explain how earthing and a fuse prevent the user from getting an electric shock.
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d) | The coffee machine has a total current requirement of 9 A. The manufacturer has 3 A, 10 A and 13 A fuses. Explain why the manufacturer fits a 10 A fuse to the coffee machine.
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Question 9
a) | 10 W is equivalent to A 10 J/C B 10 J/s C 10 J
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b) | A device is rated at 450 W, 230 V. Which fuse should be fitted to the device? A 3 A B 5 A C 10 A D 13 A
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c) | Double insulation is needed on devices which A don't use a fuse B have no earth connection C are on 24 hours a day D have no switch
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The UK Mains supply is A 230 V, 50 Hz - alternating current B 230 V - direct current C 330 V, 150 Hz - alternating current D 330 V - direct current
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