A straight wire carrying an electric current is placed along the axis of a uniformly charged ring. Will there be a magnetic force on the wire if the ring starts rotating about the wire? If yes, in which direction?

Question

Philoid · Accepted Answer

No, there won’t be any magnetic force acting on the wire in this case because, if the ring starts rotating, it will create a magnetic field which is parallel or antiparallel to the direction of current or the length vector of the wire at the center of the ring. i.e. angle between the is zero or ϖ respectively. According to F = ILBsinϴ

for ϴ = 0 or ϖ,

F= 0.

Here I is the current, L is the length of the wire and B is the magnitude of the magnetic field.

So, there will be no force on the wire if the ring starts rotating about the wire.

for ϴ = 0 or ϖ,

F= 0.

Here I is the current, L is the length of the wire and B is the magnitude of the magnetic field.

So, there will be no force on the wire if the ring starts rotating about the wire.