(a)What current is taken by a 3 kW electric geyser working on 240 V mains?
(b) What size fuse should be used in the geyser circuit?

(a) Given:

Power, P = 3 kW = 3 × 1000 = 3000 W     [converted kilowatt to watt by multiplying with 1000]

Potential difference, V = 240 V

Current, I = ?

We know that:

Then, $I=\frac{P}{V}$ 

Thus, a current of 12.5 A is taken by a 3 kW electric geyser, working on 240 V mains.

(b) The size of the fuse used in the geyser circuit should be 13 A because the rating of the fuse used in an appliance should be slightly more than the normal current drawn through it.