A bar magnet of dipole moment is free to rotate in a horizontal plane. A horizontal magnetic field exists in the space. Find the work done in rotating the magnet slowly from a direction parallel to the field to a direction 60° from the field.

Question

A bar magnet of dipole moment $10^{4} {JT}^{- 1}$ is free to rotate in a horizontal plane. A horizontal magnetic field $4 \times 10^{- 5} T$ exists in the space. Find the work done in rotating the magnet slowly from a direction parallel to the field to a direction 60° from the field.

Smart Achievers · Accepted Answer

(2)

$W = M B (\cos 0 ° - \cos 60 °) = \frac{M B}{2}$

Solution

Q.
A bar magnet of dipole moment $10^{4} {JT}^{- 1}$ is free to rotate in a horizontal plane. A horizontal magnetic field $4 \times 10^{- 5} T$ exists in the space. Find the work done in rotating the magnet slowly from a direction parallel to the field to a direction 60° from the field.

1 0.1 J

2 0.2 J

3 0.4 J

4 0.5 J

Ans.
(2)

$W = M B (\cos 0 ° - \cos 60 °) = \frac{M B}{2}$

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