Q.

A circular coil of radius 2 cm and 125 turns carries a current of 1 A. The coil is placed in a uniform magnetic field of magnitude 0.4 T. The axis of the coil makes an angle of 30° with the direction of the magnetic field. The torque acting on the coil is α×10-4 Nm. The value of α is ________.  (π=3.14)              [2026]


Ans.

(314)

τ=|M→×B→|=|NIA→×B→|

τ=125×1×π(2100)2×0.4×sin30°

   =100π×10-4 N m

So α=100π=314