A short bar magnet pleaced with its axis at `30^(@)` with a uniform external magnetic field of `0.16` Tesla expriences a torque of magnitude `0.032` Joule. The magnetic moment of the bar magnet will be

Options

A. `0.23JT^(-1)`
B. `0.40 JT^(-1)`
C. `0.80 JT^(-1)`
D. `zero`

Answer

B

Explanation

Magnetic moment of the bar magnet is given by ` tau =MB sin theta `
` :. M=( tau )/( B sin theta )=( 0.032)/( 0.16 xx sin 30^(@))=(0.032xx2)/(0.16)`
`=0.4 JT^(-1)`