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

Explanation

Given : Potential difference = 220 V.
Current = 0.45 A.
Power (W) = Potential difference(V)
x Current (A)
= `220xx0.45 W`
=99W.
The bulb must be of power 99 W. In 10 hrs,
`99Wxx10h=990` Wh.
= 0.99kWh.