A 100 turn rectangular coil $ABCD$ is hung from one arm of a balance(as shown in the figure) . A mass 500 g is added to the other arm to balance the weight of the coil . A current $4.9\;A$ passes through the coil and a constant magnetic field of $0.2 \;T$ acting inward (in xz plane) is switched on such that only arm CDof length 1 cm lies in the field . Hoe much additional mass 'm' must be added to regain the balance ?
