A metal-cased heater has an intact earth wire and a correctly fitted fuse. A fault connects the live wire directly to the case.
Which sequence explains how the protection operates?
The fuse melts, then the earth wire carries the normal operating current.
The earth wire melts, then the fuse disconnects the neutral supply wire.
The case stores charge, then the fuse transfers this charge to earth.
A large current flows through the earth wire, then the live-wire fuse melts.
81 exam-style questions on Edexcel GCSE Physics 10.4 Mains electricity, covering 10.4.1 Direct and alternating current, 10.4.2 Live, neutral and earth wires; safety, 10.4.3 Mains wire potential differences and dangers, and 10.4.4 Power ratings and energy use. Each one has a worked solution and a mark scheme showing where the marks go.