Two metal-cased appliances have identical fuses in their live wires. Their operating currents are below the fuse ratings. In P, the earth connection is intact. In Q, the earth wire is broken.
The live wire touches the case in each appliance. Nobody touches either case.
Which prediction is correct?
Both fuses must melt because both cases touch a live wire.
Only Q's fuse is likely to melt because its earth path is open.
P's fuse is likely to melt; Q's case may remain connected to live.
Neither fuse can melt because neither case is being touched.
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.