A washing machine has a metal case. It is connected to the mains supply with a cable that contains a live wire, a neutral wire and an earth wire.
A fault occurs inside the washing machine, and the live wire touches the metal case.
The earth wire has come loose and is not connected to the case.
Explain what would happen if a person touched the metal case.
Explain how a correctly connected earth wire would protect the person.
When the fault occurs, a very large current flows in the earth wire.
Explain why this current would be dangerous if it continued to flow.
A hairdryer has a plastic case and is connected with a cable that has only a live wire and a neutral wire.
Explain why the hairdryer does not need an earth wire.
16 exam-style questions on OCR GCSE Physics 8.2 Powering Earth, covering 8.2.1 Renewable and non-renewable energy resources, 8.2.2 Patterns and trends in energy use, 8.2.3 The national grid, 8.2.4 Step-up and step-down transformers, 8.2.5 Efficiency of the national grid, 8.2.6 Transformers and power transmission at high voltage, 8.2.7 The UK domestic supply, 8.2.8 Direct and alternating potential difference, 8.2.9 Live, neutral and earth wires, and 8.2.10 Dangers of mains electricity. Each one has a worked solution and a mark scheme showing where the marks go.