Blog of Veikko M.O.T. Nyfors, Hybrid Quantum ICT consultant

Quantum Mechanics demystified, a try

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Second element in electromagnetism.

There’s two types of magnetism, static and electric.

Static Magnetism

Static magnetism is the kind of magnetism where e.g. two pieces of iron attract and/or repel each other if they are brought near enough to each other.
Magnetic force is inversely proportional to the square of the distance, thus if the distance is big, the force is not big enough to cause any motion. But even in this case magnetic items are adjusting to the magnetic field to reach the minimal energy level. This is what we see with compass needle.

Static magnetism is given birth at particle level by electrons, accumulated from there first to atoms and eventually to compounds of atoms, like the horse shoe magnet and compass needle.

Electron level

Electrons have a property called Magnetic Quantum Number (m_l). This number is either positive, negative or zero, with the absolute value being that of Angular Momentum Quantum Number (l) minus 1.
Being positive, makes the electron to be ‘magnetized’ to opposite direction of a negative one. Each individual electron will then try to adjust to magnetic field around by turning towards either north or south pole of the field, depending whether m_l is positive or negative.

Atom level

Each orbital of an atom can hold maximum of two electrons. If there is two, electrons will cancel out each other’s m_l. Thus, electrons on full lower level orbitals will not cause any magnetic influence.
It’s different with the highest partially filled orbital. Or orbitals, as energywise it may be more beneficial to locate an electron not to the next free orbital in sequence but a higher one instead. Depends on case. For this reason an atom may end up having more than one partially filled orbitals in outer shell, having same magnetic quantum number.
This is what makes an atom ‘magnetic’. It will react to magnetic field around it depending whether accumulated m_l is positive or negative, by trying to align towards one or the other pole of the field. Chemical elements with partially filled outermost shell are candidates to have partially filled orbitals or unpaired electrons on more than one of it’s orbitals on outer shell. This makes the atom ‘magnetic’.
Iron, cobalt and nickel are good examples of such elements.

Compound level

When forming a compound, atoms can locate themselves magnetically oriented in the same direction or in opposite direction one by one. By nature, this is a random process, leaving the compound unmagnetized in total.
However, if an object with magnetized atoms is put in a magnetic field, it’s atoms get adjusted with the magnetic field around and object itself becomes magnetized as well. Again, Fe, Co and Ni are good examples of this.
It is believed, that natural static magnets have been born in association with a strong electric field such as one caused by lightning. Lodestone, also called magnetite, is a type of natural static magnet.

Electric magnetism

If charged object is moving in steady speed, it creates a magnetic field around it.
One can demonstrate this by setting a compass next to an electric wire. Compass needle adjusts to magnetic field immediately when electric current is turned on.

Put electric wiring around a magnetizable object, let current flow and and electric magnet is born.