Question

Find the potential difference across the resistor, when $125J$ of heat is produced each second in a $5\Omega$ resistor.

• A. 25 V
• B. 30 V
• C. 28 V
• D. 20 V

Answer 1

The correct option is A

25 V

Power dissipated is equal to the rate at which energy is consumed.
$P=\frac{H}{t}$

Also, according to Joule's law of heating, power dissipated is:
$P=\frac{V^2}{R}$

$⟹\frac{H}{t}=\frac{V^2}{R}$
$V=\sqrt{\frac{HR}{t}}$
$V=\sqrt{\frac{125\times 5}{1}}V$
$V=25V$