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JEE Main & Advanced Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर Question Bank Electric Conduction Ohms and Resistance

  • question_answer
    Equal potentials are applied on an iron and copper wire of same length.  In order to have the same current flow in the two wires, the ratio r (iron)/r (copper) of their radii must be (Given that specific resistance of iron = \[1.0\times {{10}^{-7}}\]ohm?m and specific resistance of copper = \[1.7\times {{10}^{-8}}\]ohm-m) [MP PMT 2000]

    A)            About 1.2

    B)                                      About 2.4

    C)            About 3.6                              

    D)            About 4.8

    Correct Answer: B

    Solution :

                 \[\frac{{{r}_{\text{iron}}}}{{{r}_{\text{Copper}}}}=\sqrt{\frac{{{\rho }_{\text{iron}}}}{{{\rho }_{\text{copper}}}}}=\sqrt{\frac{1\times {{10}^{-7}}}{1.7\times {{10}^{-8}}}}\approx 2.4\].


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