Question

An electric bulb is connected to a $20$ V battery of negligible internal resistance. The resistance offered by the bulb is $5$ $\Omega$. The electrical energy consumed by the bulb in $3$ hours is _____ kWh.

• A. $0.12$
• B. $0.24$
• C. $0.06$
• D. $0.03$

Answer 1

The correct option is B $0.24$

Power consumed by bulb is $P=\frac{V^2}{R}$

Energy$=E=Pt=\frac{V^2}{R}t=\frac{{20}^2}{5}W\times 3h$

$⟹E=240Wh=0.24kWh$

Answer-(B)