Question

A magnetic pole of strength 4 Am is moved twice around a long straight wire carrying a current of 3A .

The work done is

Answer 1

Answer:

The workdone is 96πx10^-7 J

Explanation:

The direction of magnetic field B is along tangent of the circular wire.

Radius of the circle is r

Carrying current is i= 3A

So B= (μ0 x i)/(2xπxr) = (μ0 x 3)/(2xπxr)

Force = m x B = (μ0 x 3 x m)/(2xπxr)

Now W= F x ((2xπxr)x 2)= (μ0 x 3 x m)/(2xπxr) x ((2xπxr)x 2) = 6π m x μ0

Angle between force and displacement = 6m π x μ0 = 6x π x 4 x (4x 10^-7)= 96πx10^-7 J