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Manipal Medical Manipal Medical Solved Paper-2007

  • question_answer
    A battery is charged at a potential of 15 V for 8 H when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 H. 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%

    Correct Answer: D

    Solution :

     Key Idea: Watt-hour efficiency of a battery is the ratio of output energy to the input energy. Input energy when the battery is charged \[=Vit\] \[=15\times 10\times 8=1200\text{ }W-h\] Energy released when the battery is discharged \[=14\times 5\times 15=1050\text{ }W-h\] Hence, W-h efficiency of battery is given by \[=\frac{energy\text{ }output}{energy\text{ }input}=\frac{1050}{1200}\] \[=0.875=87.5%\]


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