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NEET AIPMT SOLVED PAPER SCREENING 2004

  • 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 \[=Vit\] \[=15\times 10\times 8=1200\,W.\,h\] Energy released when the battery is discharged \[=\text{14}\times \text{5}\times \text{l5}=\text{1}0\text{5}0\text{W}-\text{h}\] Hence, W-h efficiency of battery is given by \[=\frac{energy\,output}{energy\,input}=\frac{1050}{1200}\] \[=0.875=87.5%\]


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