# A Path of a conducting sphere through a uniform magnetic field

1. Dec 7, 2018

### ccarleton

Hello, could someone help answer this question for me:
How would the path of a conducting sphere (i.e. AL) be affected as it passes through a strong uniform magnetic field orthogonal to the direction of motion.
I believe the Lenz effect/Eddy currents will create a magnetic field opposing the orthogonal field as it passes through it, but will every thing cancel out and the sphere continue to move in the same direction unaffected? Or will it be pushed in the direction of the magnetic field? Or will it just start spinning on its access or is there another scenario?

Thanks

2. Dec 7, 2018

### sophiecentaur

The Eddy currents would slow the ball down but I can't think of any other effect that could make a neutrally charged object to deviate from a vertical path.

3. Dec 7, 2018

### Staff: Mentor

Look for videos of a magnet falling (slowly) through a pipe. Now if the magnet is spherical shape, it's the same. If the falling object is not magnatized, but the pipe shaped object is, the result is the same.

4. Dec 7, 2018

### ccarleton

Thanks for the responses, I've seen those videos of the magnet falling through an aluminum tube. The reason I was wondering if this case would be different is because the magnet falling through the tube has the magnetic field wrapping around and hence has field lines going in the direction of motion. Would it be different in a situation with a uniform magnetic field where all field lines are orthogonal to the direction of motion?

5. Dec 7, 2018

### Staff: Mentor

Anything that creates eddy currents, puts energy into the eddies and takes energy out of kinetic energy. So qualitatively, they're all alike. Quantitatively, I don't know.

6. Dec 7, 2018

Staff Emeritus
I don't think this problem is well-specified. Is the sphere moving from a zero field to a region initially at constant field? Is the sphere placed a region of constant field before the sphere is there and then the field lines allowed to become non-uniform due to the sphere? Is the sphere ferromagnetic or only conducting? Is the setup such that the field lines are uniform after the sphere is there? Without a very specific question there is no single correct answer,

7. Dec 8, 2018

### ccarleton

Thanks for the response Vanadium, for this scenario, the pure Aluminum ball would be in free fall, starting from an area with no magnetic field. it would then cross a uniform horizontal magnetic field created between two vertically mounted plate magnets. Then exit the magnet field as it continues falling. So the question is will there be any net vertical movement of the sphere.

8. Dec 8, 2018