Question

3. 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

P= VI

100=220×I

100/220=I

5/11=I

P = VI

P = 110×5/11

P= 10×5

P=50W

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Answer 2

Answer:

25 W

Explanation:

Power = V²/R

Given that , V = 220V and P= 100W

since P= V²/R

R = V²/P

R = 220 x 220 / 100

R = 48400 /100

R = 484 ohm

When Voltage reduces to 110V ,

P = V²/R

P = 110 x 110 / 484

P = 12100 / 484

P = 25 W