#4076 Permanent Magnets

#4076 How do permanent magnets get their magnetic properties?

Permanent magnets get their properties from the behavior of electrons at an atomic level and the structural organization of those atoms into "domains." While many materials have magnetic potential, only ferromagnetic materials (like iron, nickel, and cobalt) can become permanent magnets.

1. The Atomic Source: Electron Spin

At the most fundamental level, every electron acts like a tiny magnet. This is due to two types of motion:

Electron Spin: Electrons have an intrinsic property called "spin." In most materials, electrons pair up in ways that their spins point in opposite directions, canceling each other out.
Orbital Motion: As electrons move around the nucleus, they create a tiny electric current, which generates a small magnetic field.

In permanent magnets, certain atoms have unpaired electrons. Because these spins aren't canceled out, the entire atom develops a "magnetic moment"—it becomes a microscopic bar magnet with a North and South pole.

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2. Magnetic Domains

In a block of iron that isn't yet a magnet, these "atomic magnets" aren't just floating around randomly. They naturally group into regions called domains.

Inside a single domain, billions of atoms are perfectly aligned in the same direction.
In an unmagnetized piece of metal, these domains point in different, random directions, so their magnetic fields cancel each other out globally.

3. The Magnetization Process

To turn a ferromagnetic material into a permanent magnet, the domains must be forced to point in the same direction. This is usually done through:

External Magnetic Fields: Placing the material inside a very strong magnetic field (like a solenoid).
Heating and Cooling: Heating the material allows the atoms to move more freely; as it cools within a magnetic field, the domains lock into alignment.
Manufacturing: Modern permanent magnets (like Neodymium) are often made by pressing powdered metal into a mold while exposed to a powerful magnetic field, then "sintering" (heating) them to fuse the particles together in that aligned state.

Comparison of Magnetic States

State	Domain Alignment	Net Magnetic Field
Unmagnetized	Randomly oriented	Zero
Temporary Magnet	Aligned only while near another magnet	Weak/Temporary
Permanent Magnet	Permanently aligned throughout the material	Strong and Constant

Note: A permanent magnet can lose its properties if it is heated past its Curie Temperature or struck with a heavy blow, as these actions provide enough energy to "jiggle" the domains back into random, non-magnetic orientations.

Would you like to know more about the specific manufacturing process for high-strength Neodymium magnets?

How magnets work

This video provides a clear visual explanation of how electron spin and atomic alignment create the magnetic forces we see in permanent magnets.

If a 100kg mass was suspended by rope and permanent magnet, would the magnet "wear down" over time?

The short answer is no. In a static situation where a magnet is simply holding up a weight, the magnet does not "use up" its magnetism or wear down like a battery would.

Magnetism is not a form of stored fuel or energy; it is a force field created by the structural alignment of atoms. As long as that alignment remains intact, the force remains.

Why it doesn't "run out"

To understand why the magnet doesn't get tired, it helps to compare it to gravity:

Gravity: The Earth has been pulling on the Moon for billions of years. It doesn't "run out" of gravity because gravity is a property of the Earth's mass.
Magnetism: A permanent magnet pulls on the 100kg mass because of the way its electrons are aligned. As long as those electrons stay aligned, the pull persists.

Work vs. Force: In physics, "work" is only done when an object is moved over a distance ( $W = F \cdot d$ ). Since the 100kg mass is just hanging there ( $d = 0$ ), no energy is being expended by the magnet.

What could cause it to lose strength?

While the magnet doesn't wear out from "pulling," it can lose its magnetism due to external environmental factors that disrupt the internal domain alignment:

Heat: Every magnetic material has a Curie Temperature. If the magnet is heated to this point, the thermal energy causes the atoms to vibrate so violently that they fall out of alignment.
Mechanical Shock: Dropping the magnet or hitting it repeatedly with a hammer can physically jar the domains out of alignment, weakening the field.
Opposing Magnetic Fields: Exposure to a very strong, opposite magnetic field can "force" the domains to flip or scramble.
Corrosion: For magnets like Neodymium, moisture can cause the material to oxidize (rust), which destroys the metallic structure required for magnetism.

The "Creep" of the Rope

In your specific scenario, the rope is actually much more likely to fail than the magnet. Over time, materials under constant tension undergo a process called "creep," where the fibers slowly stretch and weaken until the rope snaps. The magnet, however, will keep pulling until the end of time, provided it stays cool and dry.

Would you like to see the math for how strong a magnetic field would need to be to support a 100kg load?

Sounds like "spooky action from a distance" to me

It definitely feels that way! Watching a magnet pull an object across a table without touching it is one of the most counterintuitive things in the natural world.

However, in physics, the term "spooky action at a distance" actually belongs to a different phenomenon: Quantum Entanglement. While magnetism and entanglement both involve "invisible connections," they work in very different ways.

Magnetism vs. "Spooky Action"

Feature	Magnetism (Electromagnetism)	Quantum Entanglement ("Spooky Action")
The Mechanism	Uses a Field. The magnet creates a "field" in the space around it.	Uses Interdependence. Two particles share a single state; there is no "field" between them.
Speed	Limited by the speed of light. Changes in a magnetic field take time to travel.	Instantaneous. The correlation happens at the exact same moment, regardless of distance.
"Medium"	The field is carried by photons (virtual particles).	No known "carrier" or medium is involved.

Why Magnetism isn't actually "Spooky"

Einstein used the word "spooky" specifically because entanglement seemed to happen instantly, which violated his rule that nothing—not even information—can travel faster than light.

Magnetism, on the other hand, follows the rules of Locality:

It takes time: If you have a giant magnet 300,000 kilometers away and you flip it over, it would take exactly one second for your 100kg mass to feel the change. The force travels at the speed of light.
It has a "Handshake": Even though you can't see it, the space between the magnet and the weight is filled with magnetic flux lines. You can think of these as invisible "invisible fingers" or "tension lines" in the fabric of space.

The "Spooky" Part of Magnetism

To be fair to your intuition, there is one part of magnetism that is genuinely quantum-mechanical.

As we discussed earlier, permanent magnetism comes from electron spin. Spin is a quantum property—it’s not that the electron is literally "spinning" like a top; it just behaves as if it is. This is a fundamental "spookiness" that even classical physics couldn't explain. We only understood why magnets work after we developed Quantum Mechanics in the 20th century.

Would you like to dive deeper into how "virtual photons" actually carry the magnetic force between two objects?

From <https://gemini.google.com/app/> Google Gemini 3.0 Pro (Thinking)

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