Question

An electric tungsten bulb is connected into a home circuit. The home electric supply runs at 220 volt potential difference. When switched on, a current of 0.45 A flows through the bulb. What must be the power (wattage) of the bulb? If it is kept ‘on’ for 10 hours, how many units of electricity will be consumed?

Answer 1

Given: Potential difference = 220 V.

Current = 0.45 A.

Power (W) = Potential difference(V) × Current (A)

= 220 × 0.45W

= 99W

The bulb must be of power 99 W. In 10 hrs,

99W × 10h = 990Wh

= 0.99kWh