JEE Main & Advanced Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर JEE PYQ-Current Electricity Charging and Discharging of Capacitors

  • question_answer
    The resistance of a wire is R. It is bent at the middle by 180° and both the ends are twisted together to make a shorter wire. The resistance of the new wire is [JEE ONLINE 26-05-2012]

    A) 2R

    B) R/2

    C) R/4

    D) R/S

    Correct Answer: C

    Solution :

    [c] Resistance of wire \[(R)=\rho \frac{l}{A}\]
    If wire is bent in the middle then\[l'=\frac{l}{2'}A'=2A\]
    \[\therefore \]New resistance, \[R'=\rho \frac{l'}{A'}\]
    \[=\frac{\rho \frac{l}{2}}{2A}=\frac{\rho l}{4A}=\frac{R}{4}.\]


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