Question

The torque and magnetic potential energy of a magnetic dipole in most stable position in a uniform magnetic field

($\overrightarrow { \mathrm { m } }$) will be

• A. -mB, zero
• B. mB, zero
• C. zero, mB
• D. zero, -mB.

Answer 1

Answer: (D)

zero, -mB.

Answer 2

: Torque,$\vec { \tau } = \overrightarrow { \mathrm { m } } \times \overrightarrow { \mathrm { B } } = \mathrm { mB } \sin \theta$

and magnetic potential energy

at $\theta = 0 ^ { \circ }$ the dipole will be in most stable position $\tau = \mathrm { m } \sin \theta = \mathrm { mB } \sin 0 = 0$

and,