Two lamps, one rated $100\ W$ at $220\ V$, and the other $60\ W$ at $220\ V$, are connected in parallel to the electric mains supply. What current is drawn from the line if the supply voltage is $220\ V$?

Given:

Potential difference, $V$ = 220 V

 Power of 1st lamp, $P_1$ = 100 W

 Power of 2nd lamp, $P_2$ = 60 W

To find: Current drawn by the two bulbs, $(I)$.

Solution:

We know that formula of power is given as-

$P=V\times I$

$\therefore I=\frac {P}{V}$

Current drawn by 1st lamp is-

$I_1=\frac {P_1}{V}=\frac {100}{220}=\frac {10}{22}=\frac {5}{11}A$

Current drawn by 1st lamp is-

$I_2=\frac {P_2}{V}=\frac {60}{220}=\frac {6}{22}=\frac {3}{11}A$

Net current-

$I=I_1+I_2$

$I=\frac {5}{11}+\frac {3}{22}$

$I=\frac {5+3}{11}$

$I=\frac {8}{11}$

$I=0.73A$

The net current through the circuit is 0.73A.