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

  • question_answer Two electric bulbs, one of 200 volt 40 watt and the other 200 volt 100 watt are connected in a house wiring circuit                     [NCERT 1971; CBSE PMT 2000]

    A)            They have equal currents through them

    B)            The resistance of the filaments in both the bulbs is same

    C)            The resistance of the filament in 40 watt bulb is more than the resistance in 100 watt bulb

    D)            The resistance of the filament in 100 watt bulb is more than the resistance in 40 watt bulb

    Correct Answer: C

    Solution :

                       \[P=\frac{{{V}^{2}}}{R}\]  \[\Rightarrow {{R}_{1}}=\frac{V_{1}^{2}}{{{P}_{1}}}=\frac{{{(200)}^{2}}}{40}=1000\Omega \]            and \[{{R}_{2}}=\frac{V_{2}^{2}}{{{P}_{2}}}=\frac{{{(200)}^{2}}}{100}=400\Omega \]

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