Question Constellation Sign up for free AQA · GCSE · Combined Science · Higher
Earth wire and metal-case safety
The washing machine has a metal case. A fault causes the live wire to make an electrical connection with the metal case of the washing machine.
The earth wire is now connected to the metal case of the washing machine.
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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Marking points
- 1 Explain that charge/current flows through the earth wire instead of through the person.
- 2 Explain that the earth wire has a much lower resistance than a person.
Full-mark answer
The current flows through the earth wire instead of through the person because the earth wire has a much lower resistance than a person.
Why this answer loses marks
The earth wire is connected so the person is safe.
This does not explain the current path or the lower resistance of the earth wire.