Question

A bar magnet of magnetic moment M is placed in the magnetic field B. The torque acting on the magnet is.

• A. $M\times B$
• B. $M-B$
• C. $\frac{1}{2}M\times B$
• D. $M+B$

Answer 1

Answer: (A)

$M\times B$

Answer 2

Torque is equal to instantaneous moment of deflecting couple . The torque acting is given by $\tau =$ force $({{F}_{1}}={{F}_{2}})\times$ perpendicular distance $\tau =iBl\times b\sin \theta$ Where $i$ is current, B is magnetic field, $l$ the length and b the distance the term $ilb=M=$ dipole moment $\tau =MB\,sin\theta$ $\tau =M\times B$