If the bar magnet in exercise 5.13 is turned around by 180°, where will the new null points be located?
In this position of the magnet, the null points lie on its equatorial line, At the null point, Bequal=BH Let M be the magnetic dipole moment of the magnet and r. be the distance of the null point from the centre of the magnet. Then, 4πμ0×requal3M=BH.....(1) In ex.5.13, if raxial is the distance of the null point from the centre of the magnet, then 4πμ0×raxial32M=BH.......(2) From the equations (1) and (2), we have, requal3=2r3axial Or requal=(2)1/3raxial=1.2614=11.11cm
