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
    We have two wires A and B of same mass and same material.  The diameter of the wire A is half of that B.  If the resistance of wire A is 24 ohm then the resistance of wire B will be                                           [CPMT 2003]

    A)            12 Ohm

    B)                                      3.0 Ohm

    C)            1.5 Ohm                                 

    D)            None of the above

    Correct Answer: C

    Solution :

                 Same mass, same material i.e. volume is same or Al = constant Also, \[R=\rho \frac{l}{A}\] Þ \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{{{l}_{1}}}{{{l}_{2}}}\times \frac{{{A}_{2}}}{{{A}_{1}}}={{\left( \frac{{{A}_{2}}}{{{A}_{1}}} \right)}^{2}}{{\left( \frac{{{d}_{2}}}{{{d}_{1}}} \right)}^{4}}\]                    Þ \[\frac{24}{{{R}_{2}}}={{\left( \frac{d}{d/2} \right)}^{4}}=16\] Þ \[{{R}_{2}}=1.5\Omega \].


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