Force due to a magnetic field conceptual question

[jumbogala]

Homework Statement

A metal loop is dropped between the poles of a magnet. The pole on the left is a North pole, while the pole on the right is a South pole. Assume the magnetic field is uniform between these poles.

Does the loop feel a force? If so, what direction is that force in?

Homework Equations

The Attempt at a Solution

The magnetic field lines point from left to right (eg. North to South). The loop is entering the field, so the magnetic flux through it is increasing towards the right.

To oppose this change in magnetic flux, there is an induced current in the loop that goes in the direction of my fingers when I point my thumb towards the left.

The force felt by the loop, overall, is zero (because on one side of the loop, the force points in one direction. On the opposite side of the loop, the force points in the opposite direction. This means they cancel and the net force is zero).

Can anyone tell me if I'm completely off base here, or if I'm on the right track?

 

[anathema]

you are correct in your understanding of the situation. The loop will indeed feel a force due to the changing magnetic flux, and the direction of that force will be towards the left (opposite to the direction of the increasing flux). This is known as Lenz's Law - the induced current will create a magnetic field that opposes the change in the original magnetic field. The overall force on the loop will be zero, as you correctly stated, due to the cancellation of forces on opposite sides of the loop. Keep up the good work!

 

[nlightner]

Your explanation is correct. The loop will experience a force due to the magnetic field, known as the Lorentz force. This force will be in the direction of the induced current, which is determined by the right-hand rule you described. However, as you mentioned, the forces on opposite sides of the loop will cancel out, resulting in a net force of zero. This is because the loop is symmetric and the forces on each side are equal and opposite. Good job!