A 1 kQ heater is meant to operate at 200 V. (a) what is its resistance ? (b) How much power will it consume if the line voltage drops to 100 V? (c) how many units of electrical energy will it consume in a month (of 30 days) if it operates 10 hr daily at the specified voltage?

Explanation

The resistance of an elecric appliance is given
by `R=(V_(S)^(2))/(W) so, R=((200)^(2))/(1000)=40Omega`
(b) The actual power consumed by an electric appliance is given by
`P=((V_(A))/(V_(S)))^(2)xxW`
so, `P=((100)/(200))^(2)xx1000=250W`
(c) The total electrical energy consumed by an electric appliance in a specified time is given by
`E=(sumW_(1)h_(1))/(1000)kWh`
so, `E=(1000xx(10xx30))/(1000)=300kWh`