Figure 1 shows the inside of a plug - AQA - GCSE Physics Combined Science - Question 1 - 2020 - Paper 1
Question 1
Figure 1 shows the inside of a plug.
The plug is not wired correctly.
What should be done to connect the wires in the plug correctly?
The correctly wired plug and ... show full transcript
Worked Solution & Example Answer:Figure 1 shows the inside of a plug - AQA - GCSE Physics Combined Science - Question 1 - 2020 - Paper 1
Step 1
The plug is not wired correctly.
What should be done to connect the wires in the plug correctly?
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Answer
To correct the wiring of the plug, the blue wire should be swapped with the green and yellow wire. The blue wire must be connected to the neutral pin, while the green and yellow wire must be connected to the earth pin.
Step 2
Give the potential difference and frequency of the mains electricity supply in the UK.
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Answer
The potential difference is 230 V.
The frequency is 50 Hz.
Step 3
The washing machine is switched on.
What is the potential difference between the neutral wire and the earth wire?
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Answer
Potential difference = 0 V.
Step 4
The plug has a fuse.
Draw the circuit symbol for a fuse in the space below.
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Answer
The circuit symbol for a fuse consists of a rectangle symbolizing the fuse element with the following wiring configuration: two lines entering and exiting from the rectangle.
Step 5
Explain why it would not be safe for a person to touch the metal case.
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Answer
A person could get an electric shock because there is a current in the person and touching the metal case could lead to electrocution due to the potential difference between the earth and the live wire.
Step 6
Explain why it would now be safe for a person to touch the metal case, even if the live wire touches the metal case.
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Answer
It is safe because the charge flows through the earth wire instead of the person. The resistance of the earth wire is much less than that of a person, ensuring that the fault current will prefer to flow through the earth wire, allowing the fuse to blow and disconnect the supply before any harm can occur.
