JEE Main & Advanced Sample Paper JEE Main Sample Paper-38

  • question_answer 48) A transformer is used to light a \[140\text{ }W,\text{ }24\text{ }V\] bulb from a \[240\text{ }V\] a.c. mains. The current in the main cable is \[0.7\] A. The efficiency of the transformer is

    A)  \[63.8%\]                     

    B)  \[83.3%\]

    C)  \[16.7%\]                     

    D)  \[36.2%\]

    Correct Answer: B

    Solution :

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

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