Question

An electric fan and a heater are marked as $100W,220V$ and $1000W,220V$ respectively. The resistance of heater is:

• A. equal to that of fan.
• B. lesser than that of fan.
• C. greater than that of fan.
• D. zero.

Answer 1

The correct option is B lesser than that of fan.

From Joule's Law of heating:

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

$R=\frac{V^2}{P}$
As $V$ is same for both, so $R\propto \frac{1}{P}$
Here power of heater is more, so its resistance is lesser than that of fan.