Question

A magnet is parallel to uniform magnetic field. If it is rotated by 60o, the work done is 0.8 J. How much work is done in moving it 30o further

Answer 1

If we move it at 30 degrees further, the work done will be 0.8 x 10 (7) erg.

Solution:

Work done, W=MB(cosθ1−cosθ 2 )

When the magnet is rotated from 0° to 60°, the work done is equal to 0.8 Joule.

0.8 = MB (Cos0° - Cos 60°) = MB/2

MB = 0.8 x 2 = 1.6 N - m

In order to rotate the magnet through an angle of 30°, i.e. from 60° to 90° the work done will be:

W' = MB (Cos60° - Cos 90°)

= MB (1.2 -0 ) = MB / 2

W' = 1.6 /2 = 0.8 J

= 0.8 x 10 (7) erg.

#SPJ3