A small magnet of magnetic moment M is placed at broad side on position of a magnet of magnetic M', length 2l' in such a way that the axis of former coincides with the perpendicular bisector of the latter. The separation between their centres is d. Calculate the nature of interaction (force or couple ) among them. What is its limiting value, when d becomes very large ?

Answer

`[(mu_(0))/(4pi)xx(M'xxm)/((d^(2)+l^(2))^(3//2))=(mu_(0)M'M)/(4pi(d^(2)+l^(2))^(3//2)),(mu_(0)M'M)/(4pid^(3))]`