Question:
An electric bulb of 500 watt at 100 volt is used in a circuit having a $200 \mathrm{~V}$ supply. Calculate the resistance $R$ to be connected in series with the bulb so that the power delivered by the bulb is $500 \mathrm{~W}$.
Correct Option: 1
Solution:
500 watt at $100 \mathrm{v}$
$\mathrm{P}=\mathrm{V}_{1}$
$500=V_{i}$
$\mathrm{i}=5 \mathrm{Amp}$
$\mathrm{V}=\mathrm{i} \times \mathrm{R}$
$\mathrm{R}=20$
Ans. 1