Haryana PMT Haryana PMT Solved Paper-2007

  • question_answer
    The power dissipated across resistance R which is connected across a battery of potential V is P. If resistance is doubled, then the power becomes

    A) \[\frac{1}{2}\]                                   

    B) \[2\]

    C) \[\frac{1}{4}\]                                   

    D) \[4\]

    Correct Answer: A

    Solution :

                    Key Idea Power is inversely proportional to resistance  provided potential  difference remains constant. The rate of dissipation of electric energy is called electric power.                                 \[W=Vit\] The electric power dissipated will be is given by                                 \[p=\frac{W}{t}=\frac{Vit}{t}=Vi\]                                 \[p=\frac{{{V}^{2}}}{R}\]                    ??.(i) When resistance is doubled, then let electric power is P. \[\therefore \]  \[p=\frac{{{V}^{2}}}{2R}\]                            ??(ii) From Eqs. (i) and (ii), we get                 \[p=\frac{1}{2}p\] So, power becomes \[\frac{1}{2}\] of initial value.


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