Question

If resistance of the filament increases with temperature , what will be power dissipated in a 220 V- 100 W lamp when connected to 110 V power supply

• A. 25 W
• B. < 25 W
• C. > 25 W
• D. None of these

Answer 1

The correct option is C > 25 W

$\begin{array}{c}R=V\times \frac{V}{w}=220\times \frac{220}{100}=484\Omega \\ I=\frac{220}{484}=0.454A\\ Power=VI=110\times 0.454=50w\end{array}$