The magnetic moment of a bar magnet is 45 `Am^(2)` and its length is 10 cm. Calculate the magnetic field induction at a point 10 cm away from the centre of the magnet on the axial line.

Explanation

Length of the magnet , 2l = 10 cm `= 10 xx 10^(-2)` m
`implies l =5 xx 10^(-2) m`
Distance of the point on axial line , d=10 cm
`= 10 xx 10^(-2) m `
Magnetic moment, `M=45 Am^(2)`
`:.` Magnetic induction on the axial line of the bar magnet is `B = (mu_0)/( 4 pi ) (2MD)/((d^(2)-l^(2))^(2))`
`B = (4 pi xx 10^(-7))/(4 pi) ( 2 xx 45 xx 10 xx 10^(-2))/([(10 xx 10^(-2))^(2) - ( 5 xx 10^(-2))^(2)]^(2))`
` = 16 xx 10^(-3) T `