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

  • question_answer An electric bulb marked 40 W and 200 V, is used in a circuit of supply voltage 100 V. Now its power is [AIIMS 2002]

    A)            100W                                       

    B)            40W

    C)            20W                                         

    D)            10W

    Correct Answer: D

    Solution :

                       \[P=\frac{{{V}^{2}}}{R}\] \[\Rightarrow \frac{{{P}_{2}}}{{{P}_{1}}}=\frac{V_{2}^{2}}{V_{1}^{2}}\] (\[\because R\] is constant)            \[\Rightarrow \frac{{{P}_{2}}}{{{P}_{1}}}={{\left( \frac{100}{200} \right)}^{2}}=\frac{1}{4}\]\[\Rightarrow {{P}_{2}}=\frac{{{P}_{1}}}{4}=\frac{40}{4}=10\,W\]

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