Question

A magnet of magnetic moment $M$ is rotated through 360${}^{\circ }$ in a magnetic field $H$. Work done will be

• A. $0$
• B. $2MH$
• C. $MH$
• D. $\pi MH$

Answer 1

The correct option is A $0$

${\theta }_1=0^o$
${\theta }_2={360}^o$
$U_1=-mBcos0$
$=-mB$
$U_2=-mBcos360$
$=-mB$
$w=U_2-U_1$
$=0$