A small bar magnet has a magnetic moment `1.2 A-m^(2)`. The magnetic field at a distance `0.1 m` on its axis will be:
`(mu_(0)=4pixx10^(-7)T-m//A)`

Options

A. `1.2 xx 10^(-40T`
B. `2.4 xx 10^(-4)T`
C. `2.4 xx 10^(4)T`
D. `1.2 xx 10^(4)T`

Answer

B

Explanation

`B_(a)= (mu_(0))/(4pi) xx (2M)/(d^(3))= 10^(-7) xx (2 xx 1.2)/((0.1)^(3))= 2.4 xx 10^(-4)T`