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WB JEE Medical WB JEE Medical Solved Paper-2009

  • question_answer
    An electrical cable having a resistance of \[0.2\,\Omega \]delivers 10 kW at 200 V DC to a factory.  What is the efficiency of transmission?

    A)  65%                                      

    B)  75%

    C)  85%                                      

    D)  95%

    Correct Answer: D

    Solution :

                     Power \[P=VI\] \[\Rightarrow \]               \[I=\frac{P}{V}=\frac{10\times {{10}^{3}}}{200}=50A\] \[\therefore \] Power loss\[={{I}^{2}}R={{(50)}^{2}}\times (0.2)=500\,W\] Therefore, efficiency of transmission \[=\frac{10000\times 100}{10000+500}\] \[=95.23%=95%\,(approx.)\]


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