A short bar magnet of magnetic moment 0.4J T–1 is placed

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A short bar magnet of magnetic moment 0.4J T–1 is placed in a uniform magnetic field of 0.16 T. The magnet is in stable equilibrium when the potential energy is

1. –0.064 J
2. zero
3. –0.082 J
4. 0.064 J

Correct Option: A

For stable equilibrium
U = –MB
= – (0.4) (0.16)
= – 0.064 J