JEE Main & Advanced Physics Current Electricity, Charging & Discharging Of Capacitors Question Bank Heating Effect of Current

  • question_answer Two resistances \[{{R}_{1}}\] and \[{{R}_{2}}\] when connected in series and parallel with 120 V line, power consumed will be 25 W and 100 W respectively. Then the ratio of power consumed by \[{{R}_{1}}\] to that consumed by \[{{R}_{2}}\] will be                       [EAMCET 1983]

    A)            1 : 1                                          

    B)            1 : 2

    C)            2 : 1                                          

    D)            1 : 4

    Correct Answer: A

    Solution :

                       \[P=\frac{{{V}^{2}}}{R}\]Þ \[\frac{{{P}_{P}}}{{{P}_{S}}}=\frac{{{R}_{S}}}{{{R}_{P}}}=\frac{({{R}_{1}}+{{R}_{2}})}{{{R}_{1}}{{R}_{2}}/({{R}_{1}}+{{R}_{2}})}=\frac{{{({{R}_{1}}+{{R}_{2}})}^{2}}}{{{R}_{1}}\,{{R}_{2}}}\] Þ \[\frac{100}{25}=\frac{{{({{R}_{1}}+{{R}_{2}})}^{2}}}{{{R}_{1}}{{R}_{2}}}\] Þ \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{1}{1}\]

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