question_answer 51)

  A rectangular conducting loop consists of two wires on two opposite sides of length joined together by rods of length d. The wires are each of the same material but with cross-sections differing by a factor of 2. The thicker wire has a resistance R and the rods are of low resistance, which in turn are connected to a constant voltage source . The loop is placed in uniform a magnetic field B at 45 to its plane. Find , the torque exerted by the magnetic field on the loop about an axis through the centres of rods.   

Answer:

                  Refer Fig. 3(EP).6, force on arm AB due to magnetic field , It is acting r to the arm AB towards observer. Torque due to force  about axis EF is,                                (anticlockwise) Force on arm DC due to magnetic field, It is acting  to arm DC towards observer. Torque due to force  about axis EF is Net torque, (clockwise)