Understanding magnetism and electromagnetism

In summary, magnets are explained as being created by the flow of electrons, and electromagnets are explained as being created by a voltage source and a magnetic field. Permanent magnets are explained as being created by the displacement of electrons due to the magnetic field.
  • #1
aclark609
35
1
Natural Magnets: How do they work? I'd prefer a technical answer on a subatomic level.

Electromagnets: Say you have a copper wire hooked up to a negative terminal and on the other end of the wire a positive terminal. Due to a potential difference, electrons flow from the negative to the positive, but how does this induce magnetism?
 
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  • #2
aclark609 said:
Natural Magnets: How do they work? I'd prefer a technical answer.

Electromagnets: Say you have a copper wire hooked up to a negative terminal and on the other end of the wire a positive terminal. Due to a potential difference, electrons flow from the negative to the positive, but how does this induce magnetism?

How about you first show us what you have been reading about the subject of how magnets work? You need to show some effort here in your questions on the PF. We are happy to help clear up confusions, but you need to show us your efforts first.
 
  • #3
Well, I've read that ferrous metals are magnetic due to their electron configurations. It seems that the lone pairs in the 3d orbital somehow allow these metals to exhibit an attraction towards magnets. Perhaps it is the distance between what would be the 3d energy sublevel and 4s energy sublevel. I'm guessing it has to do with the missing lone pairs in 3d momentarily prohibiting repulsion between the electron pair in 4s, thus causing some extra "pull" from the positive nucleus on the 4s electrons along with free electrons, but I don't understand how that would allow these metals to be attracted to magnets.

As for electromagnetism, I know that an electric current generates a magnetic field, but I have no idea how. I know there is a flow of electrons in an electric current, but how does a flow of electrons create the polar attraction of a magnetic field. It doesn't make sense.
 
  • #4
I'll start with electromagnets. Amperes Law basically states that electric charges flowing (in a wire or space or wherever) create a magnetic field around their line of travel. Make a wire into a straight line and connect a voltage source and the magnetic field will be oriented in a circular fashion around the wire. If you coil the wire up, you add all of the fields together. On one side of the coil the field lines will be "leaving" and on the other side they will be "returning", since all magnetic field lines are circular. That gives a north and south pole. If you want to go deeper than taking Amperes law at face value, you'll need relativistic electromagnetics which would show you that if you traveled alongside the electrons in the wire, you would not see a magnetic field (no more moving charges) but instead an electric one. The results of any experiments would of course agree with one another but one would ascribe the effects to a magnetic field interaction and the other would see the electric field as the cause.

As for permanent magnets, the classical analog of looking at electron orbits as small current loops is a good place to start. As a classical idea its not actually correct, but can give you a first approximation as to how it works. Unbalanced outer electrons result in a net "current" and act like a loop of wire. In reality the quantum description is harder to grasp (and fills in the gaps and inconsistencies in this classical approach). In QM, the electrons have a magnetic moment due to their spin, as well as nuclear effects. But classical physics is easier to grasp and can be a good starting point.
Realize too that your idea of missing electrons prohibiting repulsions and causing "pull" from a positive nucleus is incorrect on at least two counts. For one, the atoms are (I assume) neutral, and their difference in number of electrons with the atoms of another metal is offset by more protons in the nucleus. But more importantly you're describing an electric attraction, not magnetic. Magnetic fields can align the magnetic dipoles in metals, which are usually oriented randomly. Once the metal's atomic dipoles are aligned by a magnetic field, the system wants to be in the lowest possible energy state, where their fields are closely coupled, so they "stick" together.
This is only a brief description of the concepts and I urge you to look at Wikipedia or other credible websites for the full story.
 
  • #5
Thank you for the response. I found it helpful, and yes I'll definitely read up on the subject.
 

1. What is magnetism?

Magnetism is a physical phenomenon in which certain materials have the ability to attract or repel other materials based on their magnetic properties. It is caused by the movement of electrons in atoms, which creates a magnetic field around the material.

2. What is electromagnetism?

Electromagnetism is the interaction between electricity and magnetism. It describes how electric currents create magnetic fields and how changing magnetic fields can induce electric currents.

3. What is the difference between a permanent magnet and an electromagnet?

A permanent magnet is a material that has its own magnetic field and does not require electricity to maintain it. An electromagnet, on the other hand, is created by passing an electric current through a wire, which creates a magnetic field. The strength of an electromagnet can be adjusted by changing the amount of electric current flowing through the wire.

4. How do magnets and electromagnets work?

Magnets and electromagnets both work through the movement of electrons. In magnets, the electrons in the atoms are aligned in the same direction, creating a magnetic field. In electromagnets, the electric current flowing through the wire creates a magnetic field around the wire, which can be used to attract or repel other magnetic materials.

5. What are some practical applications of magnetism and electromagnetism?

Magnetism and electromagnetism have a wide range of practical applications in our daily lives. They are used in motors and generators, speakers, MRI machines, credit cards, and many other devices. They are also used in industries such as transportation, energy, and manufacturing.

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