A short bar magnet has a magnetic moment of 0.48 J T–1. Give the direction and magnitude of the magnetic field produced by the magnet at a distance of 10 cm from the centre of the magnet on (a) the axis, (b) the equatorial lines (normal bisector) of the magnet.

Magnetic moment of the bar magnet, M = 0.48 J T−1


(a) Distance, d = 10 cm = 0.1 m


The magnetic field at distance d, from the centre of the magnet on the axis is given by the relation:




μ0 = permeability of the free space = 4 x 10-7



B1 = 0.96 x 10-4 T


B1 = 0.96 G


The magnetic field is along the S − N direction.


(b) The magnetic field at a distance of 10 cm i.e., d = 0.1 m on the equatorial line of the magnet is given as:




= 0.48 G


The magnetic field is along the N − S direction.


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