Why magnets attract or repel each other

In summary, the conversation discusses the microscopic explanation for why magnets attract or repel each other. The explanation involves the concept of tiny current loops and the influence of magnetic fields. The force on these current loops is due to the interaction between the velocity of the charges and the magnetic field. Near the poles of a magnet, the magnetic field is not uniform and this results in a net force that causes attraction or repulsion between the magnets. Despite the fact that magnetic forces do not do any physical work, there is still a force acting between the magnets, which leads to the phenomenon of attraction.
  • #1
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I would like to understand at a microscopic level why magnets attract or repel each other. I understand that there are tiny loops of currents caused by the spin and orbital rotations of electrons, that there are magnetic moments, but I don't understand why magnets attract. How is the magnetic force (F=qv x B) acting? What is doing the work since magnetic forces are not doing any work? Thank you
 
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  • #2
Consider one of the magnets (1) to be a tiny current loop, and ask how it will be influenced by the magnetic field of the other magnet (2). The force on each moving charge in the current loop is e v x B. At opposite sides of the loop the v's are equal and opposite, so in a uniform B field the force averages out to zero.

But near the pole of magnet 2 the B field is not uniform. Near the North pole the lines of B will be diverging, while near the South pole they will be converging. That means the circular loop does not just see a B field perpendicular to its plane, it also sees an additional radial component to the B field pointing outward (or inward). Since v is tangential and B is radial, v x B will be perpendicular to the plane of the loop, and the loop will be attracted (or repelled).
 
  • #3
Thank you for your answer. I think it is a good answer. I don't understand however, why, if magnetic forces don't work, there is still some work done since one magnet is able to attract another magnet. Thank you.
 

1. Why do magnets attract each other?

The attraction between two magnets is caused by their magnetic fields. Each magnet has a north pole and a south pole, and opposite poles attract each other while like poles repel each other. The stronger the magnetic field, the stronger the attraction or repulsion will be.

2. What causes magnets to repel each other?

Magnets repel each other when their magnetic fields are of the same polarity. This means that the north pole of one magnet will repel the north pole of another magnet, and the same for the south poles. This repulsion is caused by the interaction of the magnetic fields.

3. How do magnets create magnetic fields?

Magnets have microscopic magnetic domains, which are regions where the magnetic field is aligned in the same direction. When these domains are all aligned, they create a magnetic field around the magnet. This field is what causes the attraction or repulsion between magnets.

4. Can magnets attract or repel objects other than other magnets?

Magnets can attract or repel some metals, such as iron, nickel, and cobalt, which are called ferromagnetic materials. This is because these materials have their own magnetic fields that can interact with the magnetic field of the magnet. Non-magnetic materials, such as plastic or wood, will not be attracted or repelled by a magnet.

5. How does the distance between magnets affect their attraction or repulsion?

The strength of the attraction or repulsion between two magnets is inversely proportional to the square of the distance between them. This means that the closer the magnets are, the stronger the force will be. As the distance between them increases, the force will decrease. This is why magnets need to be close to each other to have a noticeable effect on each other.

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