Question

An electric bulb is rated 220v-100w. The power consumed by it when operated on 110v will be?​

Answer 1

Explanation:

Ratings of bulb = 220v - 100w

Resistance of bulb can be found out by using formula

P =V^2 /R

Where P = power

V= Potential difference

R = Resistance offered by bulb

R = V^2 /P

= 220^2 /100

= 220×220/100

= 22×22 ohm

Now, power consumed by the bulb when operated on 110V

P = V^2 /R

= 110^2 / 22×22

= 110×110 /22×22

= 10×10/2×2

= 100/4

= 25 W ANS.

HENCE, POWER CONSUMED = 25 W