Question

An electric bulb is rated 60W and 120V. Calculate the resistance of its filament when it is operating normally

Answer 1

Gives

P=60W

V=120v

We know that

$P=\frac{V^2}{R}\\R=\frac{V^2}{P}\\put value\\R=\frac{(120)^2}{60}=240\Omega$