Question

An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be -
(a) 100 W
(b) 75 W
(c) 50 W
(d) 25 W

Answer 1

Hey,

(d) 25w

Solution:-

R=V2/P

                 = (220)2/100

                 = 484 Ω

The resistance of the bulb remains constant

 if the supply voltage is reduced to 110 V then Vʹ=110 V

 the power consumed by it is given by the expression = Vʹ2/R

                                                                                                         = (110)2/484

                                                                                                       = 25w

HOPE IT HELPS YOU:-))

Answer 2

option (d) 25kw
is the correct option