Fig. 1 shows part of the circuit inside a plug fitted to a 2.3 kW kettle. The kettle is connected to a 230 V mains supply. The wires in the flex are insulat...
Question 1 Report
Fig. 1 shows part of the circuit inside a plug fitted to a 2.3 kW kettle. The kettle is connected to a 230 V mains supply. The wires in the flex are insulated and the plug has a fuse in the live wire.
(a) State the function of the fuse in this electric circuit. [2]
(b) Explain why the fuse is placed in the live wire rather than the neutral wire. [2]
(c) Calculate the current taken by the kettle when it is operating normally. [3]
(d) Which fuse rating is most suitable for this kettle: 3 A, 5 A or 13 A? [2]
Answer Details
(a) A fuse melts when the current becomes too large, breaking the circuit and stopping current to the kettle. [2]
(b) If a fuse were in the neutral wire, a fault could leave the appliance connected to the live supply. A fuse in the live wire disconnects the live supply when it melts, making the appliance safer. [2]
(c) Convert \(2.3\text{ kW}\) to \(2300\text{ W}\), then use \(I=P/V\):
\[I=\frac{2300}{230}=10\text{ A}\]
The normal current is \(10\text{ A}\). [3]
(d) A 13 A fuse is most suitable. It is the smallest available rating above the normal operating current of 10 A, so it should not melt in normal use but protects against excessive current. [2]
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