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

  • question_answer
    The resistance of 10 metre long potentiometer wire is 1ohm/meter. A cell of e.m.f. 2.2 volts and a high resistance box are connected in series to this wire. The value of resistance taken from resistance box for getting potential gradient of 2.2 millivolt/metre will be      [RPET 1997]

    A)                    \[790\,\Omega \]

    B)                                      \[810\,\Omega \]

    C)                    \[990\,\Omega \]       

    D)            \[1000\,\Omega \]

    Correct Answer: C

    Solution :

                 Potential gradient \[x=\frac{V}{L}=\frac{e}{(R+{{R}_{h}}+r)}\cdot \frac{R}{L}\]            Þ \[2.2\times {{10}^{-3}}=\frac{2.2}{(10+{{R}_{h}})}\times 1\] Þ \[{R}'=990\,\Omega \]


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