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Question: Answered & Verified by Expert
A battery is charged at a potential of 15 V in 8 h when the current flowing is 10A. The battery on discharge supplies a current of 5A for 15 h. The mean terminal voltage during discharge is 14V. What is the watt-hour efficiency of the battery?
PhysicsCurrent ElectricityJEE Main
Solution:
1475 Upvotes Verified Answer
The correct answer is: 87.5
The power of the battery, when charged is given by

P1=V1I1

The electrical energy dissipated is given by

Et=P1t1

E1=V1I1T1=15×10×8

=1200 Wh

Similarly, the electrical energy dissipated during the discharge of battery is given by

E2=V2I2t2

=14×5×15

=1050 Wh

Hence, watt-hour efficiency of the battery is given by

η=E2E1×100

=0.875×100=87.5%

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