A bar magnet of length 6 ~cm has a magnetic moment of 4 ~J ~T ⁻¹ . Find the strength of magnetic field at a distance of 200 ~cm from the centre of the magnet along its equatorial line.

Step-by-step solution

Along the equatorial line, magnetic field strength .B= ₀ 4 M (r^2+ ^2 ^ 3 / 2 . ) Given: M=4 ~J T⁻¹ r=200 ~cm =2 ~m = 6 ~cm 2 =3 ~cm =3 10⁻² ~m B= 4 10⁻⁷ 4 4 [2^2+ (3 10⁻² )^2 ]^ 3 / 2 Solving we get, B=5 10⁻⁸ tesla