Question

A magnet of magnetic moment 20 CGS units is freely suspended in a uniform magnetic field of intensity 0.3 CGS units. The amount of work done in deflecting it by an angle of ${30}^o$ in CGS units is

• A. 6
• B. $3\overline{3}$
• C. $3(2-\overline{3})$
• D. 3

Answer 1

Answer: (C)

$3(2-\overline{3})$

Work done, $W=-M{B}_{\mu }(1-cos\theta )$
$=20\times 0.3(1-cos{30}^o)$
$=61-\frac{\overline{3}}{2}=3(2-\overline{3})$