A metal-cased kettle is correctly earthed. The live wire comes loose and touches the metal case. What is the potential difference between the case and earth just after the fault?
About 0 V, because the case is joined to earth by the earth wire
About 230 V, because the case is joined to the live wire
About 230 V, because the earth wire is at the live potential
About 0 V, because no current is able to flow in the earth wire
40 exam-style questions on AQA GCSE Physics 2.3 Domestic uses and safety, covering 2.3.1 Direct and alternating potential difference and 2.3.2 Mains electricity. Each one has a worked solution and a mark scheme showing where the marks go.