Question

The work done in turning a magnet of magnetic moment m by an angle of 90° from the magnetic meridian is n times the corresponding work done to turn it through an angle of 60°. The value of n is

Answer 1

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Answer 2

Answer: N = 2

To Find: The value of N​

Explanation: Given that,

Magnetic dipole moment = M

Initial angle when magnet is rotated = 90°

W1 = MB (cos0° - cos90°)

W1 = MB

Final angle when magnet is rotated = 60°

W2 = MB(cos0° - cos60°)

W2 = $\frac{MB}{2}$

Given that,

The work done for rotating a magnet with magnetic dipole moment M, through 90° from its magnetic is N time the work done to rotate it through 60°

Therefore,

W1 = N X W2

Substituting the values,

We get,

MB = N X $\frac{MB}{2}$

N = 2 X $\frac{MB}{MB}$

Cancelling similar terms,

We get,

N = 2

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