I've been thinking that if a moving charge produces magnetic field then an electron moving around the nucleus of an atom must produce a magnetic field. And if it produces magnetic field then every matter in this universe must behave as a magnet or have some magnetic properties.

# [Physics] Does an electron produces magnetic field in an atom

electromagnetismquantum mechanics

#### Related Solutions

As was pointed out in the comments, physics answers questions within a given framework, modeled with mathematics and accepting as extra axioms laws/postulates to pick up from the mathematical solutions the ones that describe data and are predictive in new situations.

Electricity and magnetism were observed from ancient times, the word "electron" comes from the greek word for amber, because rubbing it caused electrostatic phenomena, and the word "magnet" comes from the Asia Minor region of Magnesia , where the first stones attracting and repulsing each other were found.

The theory developed slowly, with laws which described the behavior of charges and magnets, and took off with Maxwell and his equations which is classical electrodynamics.

With classical electrodynamics the behavior of electromagnets can be predicted without entering into the quantum mechanical framework.

Permanent magnets need an explanation using the spins of the quantum mechanical building blocks of matter. This framework depends on more postulates, in order to model mathematically and predict data.

The how a permanent magnet is created can be explained by how the tiny magnetic moments of electrons and nuclei had been aligned by the magnetic field of the earth during its creation, and as the metal crystallized the alignment became permanent, the tiny dipoles adding up into a large magnetic dipole. This process can be reproduced in the lab and the existing theories, classical and quantum, are very accurate in predicting the behavior.

But how exactly does an electron "spinning" create forces around the magnet?

The quantum mechanical model is a probabilistic model, the assignment of spins to electrons ( part of the axiomatic framework) and the use of the mathematics developed for electromagnetism lead to the result of magnetic forces.

Also, the magnetic force on a charge moving in the magnetic field is qvBsinθ, and its direction is perpendicular to the field and velocity of the charge. Why are these two facts true?

Because the electrodynamic models, classical and quantum mechanical, fit the observations. The two frameworks blend smoothly into each other, the classical always emerges from the quantum mechanical, but the quantum mechanical details are not needed at macroscopic levels where h_bar can be assumed to be zero.

The link you give is another mathematical transformation within the framework of quantum electrodynamics that explains the consistency of the models. It is an extra complication obscuring that electricity and magnetism are *observed input effects* that have been modeled successfully mathematically.

All macroscopic objects we observe are emergent from the underlying particle/atomic/molecular nature, which by the way follows quantum mechanical equations.

a) The reason we see electric fields is fundamentally because electrons and protons have electric charge, which generates their electric field. There are many ways that electric fields can be macroscopically induced. Analogously, the reason we see magnetic fields is because particles/atoms/molecules have magnetic dipole moments inherent in their nature, which have elementary magnetic fields.

b) A second source of electric and magnetic fields comes from the behavior of elementary and fields under motion: they obey Maxwell's equations, which tell us that changing electric fields generate magnetic fields and changing magnetic fields generate electric fields.

Say I wrapped a piece of wire around an iron bar in a closed circuit connected to a DC power supply, the electrons starts flowing and moving charge produce magnetic field.

A magnetic field is generated from the moving charges due to the laws of b), and the small dipole ferromagnetic domains described in a) orient themselves according to the external field and magnetism is retained even when the current is off. The current enhances the total magnetic field after first orientations of the dipoles.

Yet a bar magnet can produce a magnetic field without any charged particles moving around, are the magnetic fields produced by the two objects different types?

In a permanent magnet the domains after being oriented in a direction retain it because they are in the lowest energy state of the solid when oriented.

The magnetic field is the same type of field for all cases.

## Best Answer

Except for its intrinsic magnetic momentum related to its spin, an electron in an atomic orbital produces a magnetic field

only if it possesses an orbital angular momentum, which also produces a magnetic moment. Note that the QM model of the atom also has orbitals without angular momentum, in contrast to the Bohr model. Thus , e.g., the lowest electron orbital of the hydrogen atom has no magnetic momentum and magnetic field.Therefore, an electron "moving around in an atom" does not necessarily produce a magnetic field.

Note: Ferromagnetism is a solid state phenomenon related to the spin of the electron.