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JEE Main & Advanced Physics Alternating Current / प्रत्यावर्ती धारा Question Bank Self Evaluation Test - Alternating Current

  • question_answer
    A transformer is used to light a 140 W, 24 V bulb from a 240 V a.c. mains. The current in the main cable is 0.7 A. The efficiency of the transformer is

    A) \[63.8\text{ }%\]

    B) \[83.3\text{ }%\]

    C) \[16.7%\]

    D) \[36.2%\]

    Correct Answer: B

    Solution :

    [b] Power of source \[=El=240\times 0.7=166\] Efficiency \[\Rightarrow \,\,Efficiency\,=\frac{140}{166}\Rightarrow \,\eta \,=83.3%\]


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