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

Options

(a) -0.064 J
(b) zero
(c) -0.082 J
(d) 0.064 J

Correct Answer:

-0.064 J

Explanation:

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