Question

Calculate the resistance of filament of $100\mathrm{W},220\mathrm{V}$ electric bulb.

Answer 1

Step 1: Given data

Power, $\mathrm{P}=100\mathrm{W}$

Voltage, $\mathrm{V}=220\text{volts}$

Step 2: Finding Resistance of the bulb

We know that,

Power, $\mathrm{P}=\frac{{\mathrm{V}}^2}{\mathrm{R}}$ [Where V is the voltage and R is the resistance]

$\Rightarrow$ $$\begin{gathered} \mathrm{R}=\frac{{\mathrm{V}}^2}{\mathrm{P}} \\ R=\frac{{\left(220\right)}^2}{100} \end{gathered}$$

$\mathrm{R}=484\mathrm{\Omega }$

Hence, the resistance of filament bulb is $484\mathrm{\Omega }.$