Q. A battery is charged at a potential of $15\ V$ for 8 $hours$ when the current flowing is $10\ A.$ The battery on discharge supplies a current of $5\ A$ for $15\ hours.$ The mean terminal voltage during discharge is $14\ V.$ The $"Watt - hour"$ efficiency of the battery is
A) 82.5%
B) 80%
C) 90%
D) 87.5%
Explanation
(d) $Watt\ hour\ efficiency = \frac{Discharging\ energy}{Charging\ energy}$
$= \frac{14 \times 5 \times 15}{15 \times 8 \times 10} = 0.875 = 87.5\%$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.