Question

Calculate the resistance of the bulb when a 60-watt light bulb operates at a voltage of 120 V.

• A. $2\Omega$
• B. $30\Omega$
• C. $240\Omega$
• D. $72\Omega$
• E. $7,200\Omega$

Answer 1

The correct option is C $240\Omega$

Given : Power of bulb $P=60$ W

Voltage applied across it $V=120$ V

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

$\therefore$ $60=\frac{(120{)}^2}{R}$ $⟹R=240\Omega$