If a bar magnet in magnetic moment m is deflected from an angle theta in a uniform magnetic field of induction B- the work done in reversing the direction is MBsinthetaMBMB-1-costheta-MBcostheta

Question

Toppr Admin · Accepted Answer

Now lets assume that the bar magnetic is initially placed parallel to the field the initial potential energy will be $U_{i} = - - \to M . \to B = - M B cos 0 = - M B$
Now when it is deflected by an angle $θ$ then $U_{f} = - - \to M . \to B = - M B cos θ$
Now we know that the work done = $- Δ U$
$Δ U = U_{i} - U_{f}$
$Δ U = - M B (1 - cos θ)$
therefore, work done $= M B (1 - cos θ)$ .

If a bar magnet in magnetic moment m is deflected from an angle θ in a uniform magnetic field of induction B, the work done in reversing the direction is MBsinθMBMB(1−cosθ)MBcosθ

If a bar magnet in magnetic moment $m$ is deflected from an angle $θ$ in a uniform magnetic field of induction $B$ , the work done in reversing the direction is
$M B sin θ$
$M B$
$M B (1 - cos θ)$
$M B cos θ$