A short bar magnet of magnetic moment `5.25xx10^(-2)J.T^(-1)` is placed with its axis perpendicular to the earth's magnetic field . At what distance from the centre of the magnet , the magnet , the resultant field is inclined at `45^(@)` with the earth's field on
its axis Ignore the length of the magnet in comparison to the distance involved .

Explanation

`B_(ax)=(mu_(0))/(4pi).(2p_(m))/(r^('3))[ "Here " , B_(ax)=B_(H)]`
`thereforer " "r'=((mu_(0))/(4pi).(2p_(m))/(B_(eq)))^(1/3)=((10^(-7)2xx5.25xx10^(-2))/(0.42xx10^(-4)))^(1/3m)`
`= 6.3 " cm " `