Understanding the Relationship Between Electron Spin and Magnetism

[Valce]

First of all, um, do electrons actually spin (in the classical sense)? If not, how do they possesses angular momentum? From their orbit around the nucleus??


And how is all of that related to magnetism? (I.E. why does a spinning charged body interact with a magnetic field?)

I've read some stuff online, but none of it had a satisfying explanation.


Thank you!

 

[James R]

In a classical sense, electrons appear to have no size, so it doesn't really make sense to say that they spin. However, if we model an electron as having finite size, and model the charge of the electron as orbiting the centre of the electron, then the effects of that orbiting charge are similar to what we would expect for any classical orbiting charge. The charge has angular momentum, and an associated magnetic moment.

In quantum mechanics, it still makes sense to assign angular momentum to the electron, even though the electron is no longer considered to be like a little billiard ball (as it is in classical physics). A magnetic moment is still associated with the electron's angular momentum, in exactly the same way that it would be if the electron was a classical object.

To relate angular momentum with magnetism, the best way to think of it is to consider a charge moving in a small circle around a point in space. That charge produces a magnetic field, which can interact with other magnetic fields around it.

 

[R0man]

The relationship between electron spin and magnetism is a complex and fascinating topic in physics. To answer your first question, no, electrons do not actually spin in the classical sense. In classical physics, spin is defined as the rotation of an object around its axis, but electrons are not solid objects and do not have a defined shape or size. Instead, spin is an intrinsic property of particles, including electrons, and is described by quantum mechanics.

The concept of spin was first proposed in the early 1920s by physicists Wolfgang Pauli and Samuel Goudsmit and George Uhlenbeck. They observed that electrons have a magnetic moment, which means they behave like tiny magnets with a north and south pole. This magnetic moment is a result of the electron's spin, which can be thought of as an intrinsic angular momentum.

But how do electrons possess angular momentum if they are not physically spinning? This is where things get a bit tricky. According to quantum mechanics, particles like electrons have both wave-like and particle-like properties. This means that they do not have a definite position or momentum, but instead exist as a probability wave. The spin of an electron is a manifestation of this wave-like behavior, and it is an intrinsic property that cannot be fully explained by classical physics.

Now, onto the relationship between electron spin and magnetism. As mentioned earlier, electrons have a magnetic moment due to their spin. When an external magnetic field is applied, the electrons will align their spins with the field, creating a net magnetic moment. This is the basis of magnetism and is why a spinning charged body (like an electron) interacts with a magnetic field.

In summary, electron spin and magnetism are intricately linked through the quantum mechanical properties of electrons. The concept of spin allows us to understand the magnetic behavior of particles and plays a crucial role in many areas of physics, from understanding the structure of atoms to the development of modern technologies like MRI machines. I hope this explanation helps to clarify the relationship between electron spin and magnetism.