Question

A domestic lighting circuit has a fuse of 5 A . If the mains supply is at 230 V, calculate the maximum number of 36 W tube-lights that can be safely used in this circuit.

Answer 1

Let the maximum number of tube-lights be y.
Power of y tube-lights, P = 36y
V = 230 V, I = 5 A
We know that
$P=VI$
$\Rightarrow 36y=230\times 5$
$\Rightarrow y=31.94$
So, the number of tube-lights that can be safely used is 31.