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## QuestionPhysicsClass 12

A light bulb is rated at $$100W$$for a $$220 V$$ supply. Find the resistance of the bulb
.

$$484\;\text{ohm}$$
4.6
4.6

## Solution

As we know that
$$\text{Power}=VI$$
According to the question
$$P=100W$$and $$V=220V$$
By ohm's law $$V=IR$$
Current,
$$I=\frac V R$$
Than, $$P=V\times \frac{V}{R}$$
$$P=\frac{{V}^{2}}{R}$$
Resistance $$=\frac{{V}^{2}}{P}$$
$$=\frac{{\left. \left(220\right)\right. }^{2}}{100}$$
$$=484\;\text{ohm}$$