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

  • question_answer A 100 watt bulb working on 200 volt and a 200 watt bulb working on 100 volt have

    A)            Resistances in the ratio of 4 : 1

    B)            Maximum current ratings in the ratio of \[1:4\]

    C)            Resistances in the ratio of 2 : 1

    D)            Maximum current ratings in the ratio of 1 : 2

    Correct Answer: B

    Solution :

                       \[R=\frac{{{V}^{2}}}{P}\] Þ \[{{R}_{1}}=\frac{200\times 200}{100}=400\,\Omega \] and \[{{R}_{2}}=\frac{100\times 100}{200}=50\,\Omega .\] Maximum current rating \[i=\frac{P}{V}\] So \[{{i}_{1}}=\frac{100}{200}\] and\[{{i}_{2}}=\frac{200}{100}\]Þ \[\frac{{{i}_{1}}}{{{i}_{2}}}=\frac{1}{4}\].

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