Question

An electric bulb is rated $220V$ and $100W$. Power consumed by it operated on $110V$ is

Answer 1

Step 1. Given data:

Rating of the bulb,

Voltage$\left(V\right)$ = $220V$,

Power = $100W$

New voltage $\left(V_1\right)$ = $110V$.

Step 2. Formula used:

Power $P=\frac{V^2}{R}$, Where $V$= Voltage, $R$= Resistance.

Step 3. Calculations:

First, we have to determine the bulb's resistance using the given data.

As $R=\frac{V^2}{P}=\frac{{\left(220\right)}^2}{100}=484\Omega$

We will use this resistance to find power in the second case.

Hence, $P=\frac{{V^2}_1}{R}=\frac{{\left(110\right)}^2}{484}=25W$

Thus, the power consumed by it operated on $110V$ is $25W$.