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WB JEE Medical WB JEE Medical Solved Paper-2012

  • question_answer
    An electric bulb marked as \[50\,W-200\,V\]is connected across a 100 V supply. The present power of the bulb is

    A)  37.5 W          

    B)  25 W

    C)  12.5 W          

    D)  10 W

    Correct Answer: C

    Solution :

     We know that \[R=\frac{{{V}^{2}}}{P}\] Given      \[V=200V,\,P=40\,W\] and        \[V=100\,V\] Hence,   \[R=\frac{{{V}^{2}}}{P}=\frac{200\times 200}{50}\] \[P=\frac{{{V}^{2}}}{R}=\frac{100\times 100\times 50}{200\times 200}\] \[P=12.5\,W\]


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