Question

The work done for rotating a magnet with magnetic dipole moment m, by 90° from its magnetic meridian is n times the work done to rotate it by 60°. Find the value of n.

Answer 1

Answer:

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Answer 2

Answer:

The value of n = 2

Explanation:

As per the question,

Given data:

Magnetic dipole moment = m

Initial angle through which magnet is rotated = 90°

Final angle through which magnet is rotated = 60°.

Now,

Work done in rotating the magnet, through 90° is given by

W₁ = mB (cos 0° - cos 90°)

     = mB (1-0)

    = mB

Similarly,

Work done in rotating the magnet, through 60° is given by

W₂ = mB (cos 0° - cos 60°)

     = 0.5 mB

where B is the magnetic field.

As the,

Work done in rotating the magnet, through 90° is n times the work done in rotating the magnet, through 60°.

That is,

W₁ = n W₂

mB = n × 0.5 mB

∴ n = 2

Hence, the required value of n = 2.