O-LevelPhysicsElectricity5054/22 · Oct/Nov 2021 · Q47 Marks

A washing machine is working normally with both the water heater and the motor switched on. The washing machine is connected to the mains supply by a cable.

(a)(i)The current in the live wire in the cable is 13A. State the size of the current in: (i) the neutral wire in the cable current in neutral wire =[1]
(a)(ii)the earth wire in the cable. current in earth wire =[1]
(b)(i)The insulation on the mains cable is now damaged and, as the washing machine vibrates, the live wire touches the metal casing. Explain how the earth wire and the fuse together prevent any more damage.[3]
(b)(ii)Explain why it is the live wire into which the fuse is connected.[2]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.

[B1] 13 A
[B1] 0 (A)
[B1] resistance of earth wire (and casing) small or disconnects circuit or no electric shock (possible) or stops current
[B1] current in (live and) earth wire (briefly)
[B1] fuse (in live wire) blows / melts
[B1] voltage (source) disconnected (by fuse's blowing) or live voltage immediately next to (switch and blown) fuse or it / live wire at high / maximum voltage / potential
[B1] no part of the washing machine / casing is live or no current to casing

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