JEE Main & Advanced Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर Question Bank Graphical Questions

  • question_answer
    A constant current i is passed through a resistor.  Taking the temperature coefficient of resistance into account, indicate which of the plots shown in figure best represents the rate of production of thermal energy in the resistor

    A)            a

    B)            b

    C)            c

    D)            d

    Correct Answer: D

    Solution :

                       Thermal energy in resistor is \[U={{i}^{2}}Rt\] where\[R={{R}_{0}}(1+\alpha t)\]Þ\[U={{i}^{2}}{{R}_{0}}(1+\alpha t)t={{i}^{2}}{{R}_{0}}t+{{i}^{2}}{{R}_{0}}{{t}^{2}}\] So \[\frac{dU}{dt}={{i}^{2}}{{R}_{0}}(1+\alpha t)\] With the time temperature increases, hence \[dU/dt\] increases. This is best shown by curve (d).


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