A short bar magnet placed with its axis at 30º with a uniform external magnetic field of 0.25 T experiences a torque of magnitude equal to 4.5 × 10-2 J. What is the magnitude of magnetic moment of the magnet?
A short bar magnet placed with its axis at 30º with a uniform external magnetic field of 0.25 T experiences a torque of magnitude equal to 4.5 × 10-2 J. What is the magnitude of magnetic moment of the magnet?
Solution and Explanation
Magnetic field strength, B = 0.25 T
Torque on the bar magnet, T = 4.5 × 10-2 J
Angle between the bar magnet and the external magnetic field, θ = 30°
Torque is related to magnetic moment (M) as:
T = MB sin θ
∴ \(M=\frac{T}{B\sin\theta}\)
= \(\frac{4.5 \times 10^{-2}}{0.25 \times \sin 30\degree}\)= 0.36 JT-1
Hence, the magnetic moment of the magnet is 0.36 J T-1 .
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