Question

A fan draws $36\text{W}$ power when connected across $6\text{V}$ supply. Find the power if it is connected to a $2\text{V}$ supply.

• A. $4\text{W}$
• B. $6\text{W}$
• C. $8\text{W}$
• D. $2\text{W}$

Answer 1

The correct option is A $4\text{W}$

We know, power,

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

For same resistor, $P\propto V^2$

$\therefore \frac{P_1}{P_2}={\left(\frac{V_1}{V_2}\right)}^2$

$\Rightarrow \frac{36}{P_2}={\left(\frac{6}{2}\right)}^2$

$\therefore P_2=4\text{W}$