Question

A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.35 T experiences a torque of magnitude equal to 4.5 10-2 J. The magnitude of magnetic moment of the given magnet is

• A. 26 J T-1
• B. 2.6 J T-1
• C. 0.26 J T-1
• D. 0.026 J T-1

Answer 1

Answer: (C)

0.26 J T-1

Answer 2

: Here,

$\tau = 4.5 \times 10 ^ { - 2 } \mathrm {~J}$

then,

$\mathrm { m } = \frac { 4.5 \times 10 ^ { - 2 } } { 0.35 \times \frac { 1 } { 2 } } = \frac { 2 \times 4.5 \times 10 ^ { - 2 } } { 0.35 }$

$\mathrm { m } = 0.26 \mathrm {~J} \mathrm {~T} ^ { - 1 }$