A bar magnet has a length of 8cm. The magnetic field at a point at a distnace 3cm from the centre in the broadside-on position is found to be `4 xx 10^(-6) T`. Find the pole strength of the magnet.

Explanation

Magnitic field at the broadside on position
Here `2l = 8 cm d = 3 cm `
`b = (mu_(0)2l)/(4 xx (d^(2)+ l^(2))^(1//2))`
`rArr 4 xx 10^(-6) = (10^(-7)M xx 8 xx 10^(2))/(( 9 xx 10^(-4)+ 16 xx 10^(-4))^(1//2))`
`rArr 4 xx 10^(-6) = (Mxx 8xx 10^(-9))/((25)^(1//2)+ (10^(-2))^(1//2))`
`M = (4 xx 10^(-0) xx 125 xx 10^(-0))/(8 xx 10^(-9))`
`= 6.25 xx 10 - 2A - m`