Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2004

  • question_answer
    There are two electric bulbs of 40 W and 100 W. Which one will be brighter when first they are connected in series and then in parallel

    A)  40 W in series and 100 W in parallel

    B)  100 W in series and 40 W in parallel

    C)  40 W both in series and parallel will be uniform

    D)  100 W both in series and parallel will be uniform

    Correct Answer: A

    Solution :

    \[\because \]     \[H={{I}^{2}}Rt\] \[\Rightarrow \]               \[H\propto R\]                             (in series) Since, bulb having less power will have less resistance. Therefore, \[40W\]bulb will shine more brighter. Now, in parallel                 \[H=\frac{{{V}^{2}}}{R}t\] \[\Rightarrow \]               \[H\propto \frac{1}{R}\] Since, bulb having more power will have less  resistance, therefore \[100W\]bulb will shine  more brighter.


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