Question

The resistance of the hot filament of the bulb is about 10 times the cold resistance. What will be the resistance of 100 W-220 V lamps, when not in use?

Options

• 48 Ω

• 400 Ω

• 484 Ω

• 48.4 Ω

Answer 1

484 Ω

Explanation:

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

= ${\displaystyle \frac{{\left(220\right)}^2}{100}}$ 

= ${\displaystyle \frac{48400}{100}}$

= 484 Ω