Question

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

Answer 1

Here, Power $P=100W$ and Voltage $V=220V$

We know that, $P=\frac{V^2}{R}$ where $R=$ resistance

So, $R=\frac{V^2}{P}=\frac{{220}^2}{100}=484\Omega$