Fig. 10.1 depicts a metal kettle being used to heat water. It is plugged into the mains power supply, and its metal casing is earthed. A defect makes the live wire come free and touch the metal case, as shown.
(a(i))[1]
Explain why this large electric current can be dangerous.
(a(ii))[2]
Explain how a fuse protects against the danger caused by a large electric current.
(a(iii))[1]
Explain why it is unsafe to use the kettle when the fuse is fitted in the neutral wire instead of the live wire.
(b)[1]
State an appropriate fuse value. Select one from these options: $3\,\text{A}$, $5\,\text{A}$, $10\,\text{A}$ and $13\,\text{A}$.
(c)[3]
Calculate the resistance of the heating element.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Large current leads to a large heating effect / overheating / may cause fire” …