A lamp of 100 W works at 220 volts. What is its resistance and current capacity ?

Q: A lamp of 100 W works at 220 volts. What is its resistance and current capacity ?

Sol. Power of the lamp, P = 100 W

Operating voltage, V = 220 V

Current capacity of the lamp,

i = P/V = 100/220 = 0.455 A

Resistance of the lamp, $\large R = \frac{V^2}{P}$

$\large R = \frac{200^2}{100}$

R = 484 Ω