Question

An electric bulb is rated 220 V and 5 W. a) Calculate the current required. b) Calculate the resistance of its heating element. c) When it is operated on 110 V, what will be the power consumed?

Answer 1

Answer:

Given :; -

Volt = 220 v

Power = 5W

To Find ,

Current = i ( let )

Resistance = r ( let )

Power consumed when operated on 110 v = p ( let )

We know that ,

P = v * i

5 = 220 * i

i = 5/220

i = 0.023 A (approx)

Also ,

P = v^2/r

5 = 220 * 220 /r

r = (220 * 220)/5 ..............(1)

r = 9680 ohm

When bulb is used in 110v the power consumed is =

p = v^2/r

p = (110*110*5)/(220*220)

p = 1.25 W