Question

An electric bulb is rated as 400 W, 250 volt (i) find the rated current
(ii) if the bulb is connected to a 200 V supply, find its power

Answer 1

Given : $V=250$ volts $P=400$ W $V_s=200$ volts

(i) : Rated current $I=\frac{P}{V}=\frac{400}{250}=1.6$ A

(ii) : Power $P^{\prime }=V_{s}I=200\times 1.6=320$ W