5.3. A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.25 T experiences a torque of magnitude equal to . What is the magnitude of magnetic moment of the magnet?
The angle between axis of bar magnet and external magnetic field, θ = 30°
Magnetic field strength, B = 0.25 T
Torque on the bar magnet, Τ = 4.5 x J
Torque experienced by a bar magnet placed in a uniform magnetic field is:
T = m x B = mBsin
m = 0.36
Hence, the magnitude of the moment of the Bar magnet is 0.36 .