A short bar magnet of magnetic moment m=0.32 J T- 1 is placed in a uniform magnetic field of 0.15 T . If the bar is free to rotate in the plane of the field, What is the potential energy of the magnet in unstable position?

Question

A short bar magnet of magnetic moment m=0.32 J T- 1 is placed in a uniform magnetic field of 0.15 T . If the bar is free to rotate in the plane of the field, What is the potential energy of the magnet in unstable position? (A) 4.8× 10- 2J (B) 9.6× 10- 2 J (C) 2.4× 10- 2 J (D) 1.2× 10- 2 J

Tardigrade Admin · Accepted Answer

For the unstable equilibrium, the angle between the magnetic moment and magnetic field is 180^o. (

∵

In this position it will be in a direction to magnetic field thus no torque will act on it.)

θ = 18 0^{o}

The potential energy of the magnet

U = - m B cos 18 0^{^{\circ}}

= - 0.32 \times 0.15 (- 1) = 4.8 \times 1 0^{- 2} J

Thus, for the unstable equilibrium, the potential energy is

4.8 \times 1 0^{- 2} J

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Q. A short bar magnet of magnetic moment $m = 0.32 J T^{- 1}$ is placed in a uniform magnetic field of $0.15 T$ . If the bar is free to rotate in the plane of the field, What is the potential energy of the magnet in unstable position?

$4.8 \times 1 0^{- 2} J$

$9.6 \times 1 0^{- 2} J$

$2.4 \times 1 0^{- 2} J$

$1.2 \times 1 0^{- 2} J$

Q. A short bar magnet of magnetic moment m=0.32JT−1 is placed in a uniform magnetic field of 0.15T . If the bar is free to rotate in the plane of the field, What is the potential energy of the magnet in unstable position?

4.8×10−2J

9.6×10−2J

2.4×10−2J

1.2×10−2J

Q. A short bar magnet of magnetic moment $m = 0.32 J T^{- 1}$ is placed in a uniform magnetic field of $0.15 T$ . If the bar is free to rotate in the plane of the field, What is the potential energy of the magnet in unstable position?

$4.8 \times 1 0^{- 2} J$

$9.6 \times 1 0^{- 2} J$

$2.4 \times 1 0^{- 2} J$

$1.2 \times 1 0^{- 2} J$