Two electric bulbs have the following specifications.(i) 100 W at 220

1.	Two electric bulbs have the following specifications.(i) 100 W at 220 V (ii) 1000 W at 220 V.Which bulb has higher resistance? What is the ratio of their resistances?
Answer» The resistance of filament, \(R=\frac{V}{I}=\frac{V^2}{P}\) At constant voltage V, the resistance \(R\,\infty\,\frac{1}{P}\) That is the resistance of filament of 100 W bulb is greater than that of 1000 W bulb. The ratio of resistances \(=\frac{R_1}{R_2}=\frac{P_2}{P_1}=\frac{1000}{100}=\frac{10}{1}=10:1\)

Two electric bulbs have the following specifications.(i) 100 W at 220 V (ii) 1000 W at 220 V.Which bulb has higher resistance? What is the ratio of their resistances?

Answer»

The resistance of filament,

\(R=\frac{V}{I}=\frac{V^2}{P}\)

At constant voltage V, the resistance

\(R\,\infty\,\frac{1}{P}\)

That is the resistance of filament of 100 W bulb is greater than that of 1000 W bulb.

The ratio of resistances

\(=\frac{R_1}{R_2}=\frac{P_2}{P_1}=\frac{1000}{100}=\frac{10}{1}=10:1\)