question_answer 50)

    A 100 turn rectangular coil ABCD (in XY plane) is hung from one arm of a balance (Fig. 3(EP).5). A mass 500 g is added to the other arm to balance the weight of the coil. A current A passes through the coil and a constant magnetic field of T acting inward (in xz plane) is switched on such that only arm CD of length 1 cm lies in the field. How much additional mass 'm' must be added to regain        the balance?

Answer:

                    When the magnetic field is off and the weight added in one pan of a balance, balances the rectangular coil in the other pan of balance. Then                 When current  is passed through the coil and the magnetic field is switched on, let m be the mass added in a pan to balance the beam. Then or