Question

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

Answer 1

Answer:

Answer 50 watt

Explanation:

Power of bulb = 100 w

Voltage = 220 v

Then current drawn by bulb is :-

P = V × I

$= > 100 = 220 \times i$

$i = \frac{100}{220}$

$= > i = 0.45ampre$

Now voltage = 110

Current = 0.45 A

then power of bulb will be :-

$p = vi$

$= > p = 110 \times \frac{45}{100}$

$= > p = 50watt$

hence, power consumed by bulb is 50 w

Answer 2

Answer:

Power = 100 W

Voltage=220 V

Power=voltage² / resistance

Resistance=V²/P=48400/100=484 Ω

Voltage(2)=110 V

Resistance remains constant=484Ω

Power=V²/R=12100/484=25 W