A bar magnet when placed at an angle of `30^(@)` to the direction of magnetic field field induction of `5xx10^(-2)T`, experiences a moment of couple `25xx10^(-6) N-m`. If the length of the magnet is 5cm its pole strength is

Options

A. `2 xx 10^(-2) A- m`
B. `5 xx 10^(-2) A-m`
C. `2A-m`
D. `5 A-m`

Answer

A

Explanation

`tau= (q_(m)l) B sin 30^(@)`
`rArr q_(m)= (25 xx 10^(-6))/(0.05 xx 5 xx 10^(-2) xx (1)/(2))= 2 xx 10^(-2) A- m`