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A battery is charged at a potential fo 1...

A battery is charged at a potential fo 15 V for 8 h when the current folwing is 10A. The battery on discharge supplies a current of 5A fo 15h . The mean terminal voltage during discharge is 14V. The watt-hour efficiency of the battery is

A

`80% `

B

`90%`

C

`87.5% `

D

`82. 5% `

Text Solution

Verified by Experts

The correct Answer is:
C
The power of the battery, when charged, is given by `P_(1) = V_(1)I_(1)` The electrical energy dissipated is given by `E_(1) = P_(1) t_(1)`
i.e ., `E_(1) = P_(1) I_(1) t_(1)= 15 xx 10 xx 8 `
=1200 Wh
Similarly, the electrical energy dissipated during the discharge of battery is given by
`E_(2) = V_(2) I_(2) t_(2) = 14 xx 5 xx 15 `
= 1050 Wh
Hence, watt-hour efficiency of the battery is given by
`eta = (E_(2))/(E_(1)) xx 100 = 0.875 xx 100 = 87 .5 % `
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Knowledge Check

  • 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 erminal voltage during discharge is 14 V. The "Watt-hour" efficiency of the battery is

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

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    C
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