A magnetic dipole of magnetic moment `0.72 Am^2` is placed horizontally with the north pole pointing towards south. Find the position of the neutral point if the horizontal component of the earth's magnetic field `18 muT`.

Explanation

When the magnet is such that the its north poole faces the geographic south of earth , the natural point lies along the axial line of the magnet
`So (mu_(0))/(4 pi) (2M)/(d^(3)) = 18 xx 10^(-6)`
`rArr (10^(-7) xx 2 xx 0.72)/(d^(3)) = 18 xx 10^(-6)`
`rArr d^(3) = (2 xx 0.72 xx 10^(-7))/(15 xx 10^(-6))`
`d = ((8 xx 10^(-8))/(10^(-6)))^(1//3)`
`= 2 xx 10^(-1) m = 20cm`