Question

A short bar magnet of magnetic moment 0.5J/T is placed with its axis is 30° to a uniform magnetic of 0.1T.

Answer 1

(i) We know τ = MBsinθ
where τ = Torque acting on a short bar magnet
M = Magnetic moment
B = Magnetic field
τ = 0.5 × 0.1 × sin30° 

= 0.5 × 0.1 × 1/2 = 2.5 × 10–2Nm
(ii) The direction of torque is always perpendicular to the plane containing magnetic moment and magnetic field (vector M x vector B).