A short bar magnet placed with its axis at `30^@` with an external field of 0.25 T experiences a torque of magnitude to `4.5xx10^(-2)J` . What is the magnitude of magnetic moment of the magnet ?

Explanation

`theta=30^@, B = 0.25T, tau=4.5xx10^(-2)J, " "m=? " "tau=mBsintheta`
`:.m=tau/(Bsintheta)=(4.5xx10^(-2))/(0.25xxsin30^@)=(4.5xx10^(-2)xx2)/(0.25)=36.0xx10^(-2)=0.36Am^2(" or" JT^(-1))`