NEET Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर NEET PYQ-Current Electricity Charging Capacitors

  • 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:                                                                                                                                     [AIPMT (S) 2004]

    A)        82.5%            

    B)       80%    

    C)  90%                

    D)       87.5%

    Correct Answer: D

    Solution :

    [d] 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
    \[=14\times 5\times l5=1050W-h\]
    Hence, W-h efficiency of battery is given by
    \[\text{=}\frac{\text{energy}\,\text{output}}{\text{energy}\,\text{input}}\text{=}\frac{\text{1050}}{\text{1200}}\]
    \[=0.875=87.5%\]


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