Question

AN ELECTRIC BULB IS RATED 220V AND 100W, WHEN IT IS OPERATED AT 110V,THE POWER WILL BE​

Answer 1

The power consumption of an Electric bulb which is rated 220V & 100W is given by the following relation:

begin mathsize 12px style straight P equals straight V squared over straight R

100 equals 220 squared over straight R

straight R equals 48400 over 100 equals 484 space straight capital omega end style

Where 'P' is the power rating, 'V' is the voltage at which the bulb functions and 'R' is the resistance provided

by that bulb to the flow of current across the circuit.

-Therefore, the resistance 'R' due to the bulb is 484 Ohm

-Now when the same bulb is used across the voltage of 110 V, the power consumed by this bulb is given by

begin mathsize 12px style straight P equals straight V squared over straight R

straight P equals 110 squared over 484

straight P equals 12100 over 484 equals 25 space Watt end style

-Therefore, the Power consumed by this bulb across 110 V is 25 Watts