A bar magnet of magnetic moment `vec(M)` is placed in a magnetic field of induction `vec(B)` . The torque exerted on it is

Options

A. `M xx B `
B. `-B*M`
C. `M*B`
D. `M+B`

Answer

A

Explanation

When a bar magnet of magnetic moment M is placed in a magnetic field of induction B , then net force on it is `F_(R)=mB+(-m)B=0`

While torque , `tau=mB xx 2l sin theta =MB sin theta `( as M=2ml)
i.e., ` tau = M xx B`