What is the magnitude of the equatorial and axial fields due to a bar magnet of length 5.0 cm at a distance of 50 cm from its mid-point? The magnetic moment of the bar magnet is 0.40 A `m^2`, the same as in Example 5.2.

Explanation

For a short bar magnet its magnetic field at a far equatorial point is,
`B_e = (mu_0)/( 4 pi) ((m)/( r^3) )`
`therefore B_e = (4 pi xx 10^(-7) ) /( 4 pi) xx (0.4 )/( (0.5)^(3) )`
`therefore B_e = 3.2 xx 10^(-7) T`
For a short bar magnet, its magnetic field at a far axial point is,
`B_a = (mu_(0) )/( 4 pi ((2m) /( r^3))`
`therefore B_a = (4pi xx 10^(-7) )/( 4 pi) xx (2 xx 0.4)/( (0.5)^(3) )`
`therefore B_a = 6.4 xx 10^(-7) T`