In a two dimensional `x – y` plane, the magnetic field lines are circular, centred at the origin. The magnitude of the field is inversely proportional to distance from the origin and field at any point P has magnitude given by `B = k /r` , where k is a positive constant. A wire carrying current I is laid in xy plane with its ends at point A `(x_(1), y_(1)` and point B `(x_(2)), y_(2))`. Find force on the wire.

Answer

`vec(F)=(kl)/2 l n(x_(2)^(2)+y_(2)^(2)/x_(1)^(2)+y_(1)^(2)) hat(k)`