Question

What is the resistance of the electric bulb rated 120 W, 220 V?

• A. 1.8 ohm
• B. 65.4 ohm
• C. 403.3 ohm
• D. 500 ohm

Answer 1

The correct option is C 403.3 ohm

Power rating of bulb, $P=120W$,
Voltage rating of bulb, $V=220V$.
Let the resistance of bulb R.
We know,
$P=\frac{V^2}{R}$

$R=\frac{V^2}{P}=\frac{{220}^2}{120}$

$R=403.3ohm$