A bar magnet having a magnetic moment of `2xx10^(4) JT^(-1)` is free to rotate in a horizontal plane. A horizontal magnetic field `B=6xx10^(-4) T` exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction `60^(@)` from the field is

Explanation

`W = MB [ cos theta_(1) - cos theta_(2)]`
`= 2.0 xx 10^(4) xx 6 xx 10^(-5) [ cos 0^(@) - cos 60^(@)]`
`= 2 xx 10^(4) xx 6 xx 10^(-5) [ 1 - (1)/(2)]`
`= (12)/(2) xx 10^(-1)`
`= 0.6 J`