2004 AIPMT Current ElectricityElectrical Energy and Efficiency Easy Question 115 of 130 in Current Electricity

A battery is charged at a potential of 15V for 8 hours when the current flowing is 10A. The battery on discharge supplies a current of 5A for 15 hours. The mean terminal voltage during discharges is 14 V. The "Watt hour" efficiency of the battery is :-

A 80%
B 90%
C 87.5%
D 82.5%

The answer is C.

Solution

Watt-hour efficiency $= \dfrac{\text{energy given out on discharge}}{\text{energy supplied while charging}} \times 100$
Energy in (charging) $= V I t = 15 \times 10 \times 8 = 1200$ Wh
Energy out (discharging) $= 14 \times 5 \times 15 = 1050$ Wh
Efficiency $= \dfrac{1050}{1200} \times 100 = 87.5$ percent
So the watt-hour efficiency of the battery is 87.5%.

Concept Watt-hour efficiency

Current Electricity in past papers

130 questions from this chapter have appeared across 27 exam years.