Question:
An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it ?
(a) 1 A
(b) 2 A
(c) 4 A
(d) 5 A
Solution:
(d).
Explanation : $\mathrm{P}=\mathrm{VI}$ or $\mathrm{I}=\frac{\mathrm{P}}{\mathrm{V}}=\frac{1 \mathrm{~kW}}{220 \mathrm{~V}}$
$=\frac{1000 \mathrm{~W}}{220 \mathrm{~A}}=4.55 \Omega=5 \mathrm{~A}$