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

  • question_answer
    Six equal resistances are connected between points P, Q and R as shown in the figure. Then the net resistance will be maximum between                                   [IIT-JEE (Screening) 2004]

    A)         P and Q

    B)         Q and R

    C)         P and R

    D)         Any two points

    Correct Answer: A

    Solution :

                                             Resistance between P and Q \[{{R}_{PQ}}=R||\left( \frac{R}{3}+\frac{R}{2} \right)\]\[=\frac{R\times \frac{5}{6}R}{R+\frac{5}{6}R}\]\[=\frac{5}{11}R\] Resistance between Q and R \[{{R}_{QR}}=\frac{R}{2}||\left( R+\frac{R}{3} \right)\]\[=\frac{\frac{R}{2}\times \frac{4R}{3}}{\frac{R}{2}+\frac{4R}{3}}\]\[=\frac{4}{11}R\] Resistance between P and R \[{{R}_{PR}}=\frac{R}{3}||\left( \frac{R}{2}+R \right)\]\[=\frac{\frac{R}{3}\times \frac{3R}{2}}{\frac{R}{3}+\frac{3R}{2}}\]\[=\frac{3}{11}R\] Hence it is clear that \[{{P}_{PQ}}\] is maximum.


You need to login to perform this action.
You will be redirected in 3 sec spinner