# Deflection of magnetic dipoles by a magnetic field

• snoopies622
In summary, the conversation discusses the confusion surrounding the Stern-Gerlach experiment and how a magnetic field can deflect particles with magnetic dipoles instead of just rotating them. The explanation for this is that the magnetic field is non-uniform and can cause a net attractive force on the dipole. The conversation also mentions the use of analogies, such as gravitational tidal forces, to better understand the concept.
snoopies622
I'm reading about the Stern–Gerlach experiment and the only part that confuses me is how a magnetic field would deflect particles with magnetic dipoles instead of just rotating them. In this case the magnetic field is non-uniform, but it still seems intuitively strange to me since magnetic field lines around the particles are always closed, and so I imagine that any magnetic field would have a kind of translational net zero effect on them. Would this translational force also appear if I tossed a macroscopic bar magnet through a non-linear magnetic field? (Say, one that always pointed in the same direction but increased in strength in a spacially linear way.)

snoopies622 said:
I'm reading about the Stern–Gerlach experiment and the only part that confuses me is how a magnetic field would deflect particles with magnetic dipoles instead of just rotating them.
Suppose you are near the North Pole of your external non-uniform field. In that case your dipole’s North Pole will be repelled and the dipole’s South Pole will be attracted. However, since the South Pole will be closer to the external magnet the field there will be stronger than at the dipole’s North Pole, so the attraction of the South Pole will be stronger than the repulsion of the North Pole and you will have a net attractive force.

Thanks, Dale. It makes sense analytically but I guess I'll have to do some imagining and drawing pictures for it to work for me intuitively. I'm finding that thinking of gravitational tidal forces is a helpful analogy.

## What is a magnetic dipole?

A magnetic dipole is a fundamental unit of magnetism, consisting of a north and south pole separated by a small distance. It can be thought of as a small bar magnet.

## How does a magnetic field affect a magnetic dipole?

A magnetic field exerts a force on a magnetic dipole, causing it to align with the field. This alignment can result in the dipole experiencing a torque or a force depending on its orientation relative to the field.

## What is meant by "deflection" of a magnetic dipole?

Deflection refers to the change in direction or orientation of a magnetic dipole when it is subjected to a magnetic field. This can occur due to the torque or force exerted on the dipole by the field.

## What factors affect the deflection of a magnetic dipole by a magnetic field?

The strength and direction of the magnetic field, the strength and orientation of the magnetic dipole, and the distance between the dipole and the field all play a role in determining the deflection of the dipole.

## What are some real-world applications of the deflection of magnetic dipoles by a magnetic field?

This phenomenon is utilized in various technologies such as magnetic compasses, electric motors, and magnetic resonance imaging (MRI) machines. It also plays a role in the behavior of charged particles in Earth's magnetic field and the interaction of solar wind with Earth's magnetic field.

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