Question

Which of the following is correct for work done in the deflection of a magnet in a uniform magnetic field ?
(A) - W = MB (1 - cos 0) (B) W = MB (1 - sino) (C) W = MB (cos 0 - 1) (D) W = MB (sin0 - 1) ​

Answer 1

Answer:

B is the correct answer. ) W = MB (1 - sino)

Answer 2

A) W= MB(1-cosθ)

Let's say if the bar magnet is placed parallel to the field initially

we can say that initial potential energy will be

Ui= - M.B= -MBcosθ

here θ will be the angle between the bar magnet and the field lines which will be 0 initially.

After the deflection of θ angle

potential energy will be

Uf= - MBcosθ

We know that work done = - change in potential energy

W= Ui-Uf= - MB( cosθ -1 )

W= MB( 1-cosθ )

Therefore, work done in the deflection of a magnet in a uniform magnetic field will be W= MB( 1-cosθ ).