You may ask, how magnets work. Magnets have a hidden force that pulls some metals close or pushes them away. This hidden force is called a magnetic field. When you put a fridge magnet on your fridge or use a compass, you see magnets in action every day. Understanding how magnets work helps explain why magnetic things can pull or push each other because of tiny magnetic pieces inside them.
Table of Contents
Key Takeaways
- Magnets make invisible magnetic fields. These fields can pull or push some metals like iron, cobalt, and nickel. Electron spins inside atoms help make things magnetic. Groups of atoms called magnetic domains also help. Magnets have two poles. These are called north and south. Opposite poles attract each other. The same poles push away from each other. There are three main types of magnets. Permanent magnets keep their power. Electromagnets need electricity to work. Temporary magnets only work near strong magnetic fields. Magnet strength depends on many things. These include material, size, shape, and temperature. How you store magnets also matters. Keeping magnets cool and stored right helps them last longer.
What Are Magnets
Have you ever thought about what magnets are? A magnet is a special thing that makes its own magnetic fields. These fields are invisible spaces around the magnet. In these spaces, the magnet can pull or push some metals. You can find magnets in many places. For example, they hold notes on your fridge. The needle in a compass is also a magnet and always points north.
Magnets are different from other things because they can pull or push metals like iron, nickel, and cobalt. Scientists sort materials by how they act with magnetic fields:
- Ferromagnetic and ferrimagnetic materials: These can stay magnetic and are pulled strongly by magnets.
- Paramagnetic materials: These are pulled a little by magnetic fields, but you need special tools to see it.
- Diamagnetic materials: These are pushed away by magnetic fields, but the push is very weak.
Magnetic Fields
Magnetic fields are invisible forces around magnets. You cannot see them, but you can see what they do. For example, if you put iron filings near a bar magnet, the filings make lines. These lines show the shape of the magnetic field. Magnetic fields come from moving electric charges, like electrons spinning in atoms. You can also find magnetic fields around wires with electric current.
You can use a compass or special sensors to measure magnetic fields. A compass needle turns to match the Earth’s magnetic fields, so you can find your way. Some cool tools, like augmented reality apps, let you see magnetic fields as colors on a screen. In real life, you see magnetic fields working in maglev trains, speakers, and even in shake flashlights.
Magnetic Poles
Every magnet has two ends called north and south poles. The magnetic fields are strongest at these ends. The north and south poles decide how magnets pull or push each other. If you put the north pole of one magnet near the south pole of another, they pull together. If you put two north poles or two south poles together, they push apart.
You can find the north and south poles on a bar magnet by hanging it on a string. The end that points to Earth’s north is the magnet’s north pole. If you cut a magnet in half, each piece will still have a north and south pole. This rule helps you see why magnets always have two poles and why magnetic fields go from one pole to the other.
How Magnets Work
Electron Spin
You might ask how magnets work deep inside. The answer starts with electrons. Electrons are tiny parts inside every atom. Each electron spins like a top. This spin makes a small magnetic moment, like a mini magnet. Electrons move around the nucleus in orbits. Their movement and spin both make magnetic effects.
Not all electrons help with magnetism. If two electrons spin in opposite ways, their magnetic fields cancel out. Only unpaired electrons with the same spin add to the atom’s magnetic field. This is why some things are magnetic and others are not.
The Stern-Gerlach experiment showed that atoms with unpaired electrons split into two beams in a magnetic field. This experiment proved that electron spin makes a real magnetic effect.
When many atoms have unpaired electrons spinning the same way, the material can become magnetic. This is the first step to understanding how magnets work.
Magnetic Domains
Now, let’s look at how magnets work in bigger pieces. In iron, nickel, and cobalt, atoms group in areas called magnetic domains. Inside each domain, many atoms’ magnetic moments line up together. A domain is a small part where all the mini magnets point the same way.
- If the domains point in random ways, the material is not a magnet.
- If you put the material in a strong magnetic field, the domains start to turn and line up.
- As more domains line up, the material becomes magnetized and acts like a magnet.
After you take away the magnetic field, some domains stay lined up. This is why iron can stay magnetic after you remove the magnet. Scientists call this effect hysteresis.
You can see magnetic domains in a few ways:
- The Barkhausen effect shows sudden jumps in magnetism as domain walls move.
- Special microscopes let you see domain patterns on magnetic materials.
- If you sprinkle magnetic powder on a magnet, you see patterns that match the domains inside.
The atomic structure of a magnet, and how electrons spin and line up, controls how strong the magnet is. When most domains point the same way, you get a strong magnet. If you heat a magnet above the Curie temperature, the domains lose their order and the magnetism goes away.
To understand how magnets work, you need to look at both electron spin and magnetic domains. These two ideas explain why magnets pull or push and why some things can become magnets but others cannot.
Why Magnets Attract or Repel
Attraction and Repulsion
Magnets can pull together or push apart. This happens because each magnet has a north and a south pole. If you put a north pole near a south pole, they pull together. If you put two north poles or two south poles together, they push away. This is because of the magnetic field around each magnet.
- Atoms have electrons that spin and make small magnetic effects.
- Most materials have spins that cancel out, so they are not magnetic.
- Magnetic materials have many electrons spinning the same way, making a strong field.
- When two magnets are close, their fields interact. Opposite poles pull together, and like poles push apart.
Magnetic forces work like electric charges. Like charges push away, and unlike charges pull together. The force gets weaker if you move the magnets farther apart, just like Coulomb’s law for electric forces.
If you try to push two like poles together, you feel them push back. That is energy turning into movement, so the magnets move apart. If you bring opposite poles together, the force pulls them close.
Materials Magnets Attract
Not all metals stick to magnets. You might see a magnet pick up a paperclip but not a coin. This is because of how atoms are made.
Materials that magnets attract have unpaired electrons. These electrons make magnetic dipole moments. In some metals, like iron, cobalt, and nickel, the electron spins line up in groups called domains. This makes the metal strongly magnetic.
Here is a table to show which materials magnets attract and why:
| Material Type | Examples | Magnetic Behavior |
|---|---|---|
| Ferromagnetic Metals | Iron, Cobalt, Nickel, Steel | Strongly attracted; unpaired electrons line up in domains, making them magnetic. |
| Rare Earth Magnets | Neodymium, Samarium-Cobalt | Very strong magnets; unpaired electrons make powerful magnetic fields. |
| Paramagnetic Metals | Aluminum, Platinum, Manganese | Weakly attracted; only show magnetism in a magnetic field, not permanent. |
| Diamagnetic Metals | Copper, Gold, Silver | Weakly pushed away; all electrons paired, so no lasting magnetic effect. |
You can try this at home. Use a magnet to pick up different things. You will see only some metals stick. The reason is in the atoms and how the electrons spin and line up to make a magnetic field.
Types of Magnets
There are three main types of magnets you see every day. These are permanent magnets, electromagnets, and temporary magnets. Each type works in its own way and has special uses. Knowing how they are different helps you see how magnets work in things like fridges and big machines.
Permanent Magnets
Permanent magnets keep their magnetic power for a long time. They do not need extra energy or electricity to work. Their atoms stay lined up, so they always make a magnetic field. You can find permanent magnets in fridge magnets, headphones, and motors.
There are different groups of permanent magnets. Some common ones are ferrite (ceramic), Alnico, neodymium, and samarium-cobalt. Neodymium and samarium-cobalt are rare earth magnets. They are much stronger than other types of magnets for their size. The table below shows how some popular permanent magnets compare:
| Magnet Type | Composition | Magnetic Strength | Temperature Tolerance | Corrosion Resistance | Typical Applications |
|---|---|---|---|---|---|
| NdFeB (Neodymium) | Nd2Fe14B intermetallic compound | Very high (BHmax > 10x ferrite) | Up to ~200°C | Poor, needs coating | Electronics, motors, industrial uses |
| Samarium Cobalt | Sm, Co, rare earth metals | High (14-28 MGOe) | Up to 350°C | High | Aerospace, sensors, motors |
| AlNiCo | Aluminum, Nickel, Cobalt, Iron | Moderate | Up to 600°C | Good | Instruments, high-temp uses |
| Ferrite (Ceramic) | Iron oxide with barium/strontium | Low | Lower temp range | Good | Consumer products, speakers |
Tip: Neodymium magnets are the strongest type, but they can break or rust fast. Alnico magnets are good for hot places.
You can see how strong these magnets are in this chart:
Electromagnets
Electromagnets only make a magnetic field when electricity goes through them. You make one by wrapping wire around a metal core and sending electric current through the wire. You can turn the magnet on or off by starting or stopping the current. This makes electromagnets useful in many things.
You can find electromagnets in:
- Electric motors and generators
- Speakers and headphones
- MRI machines in hospitals
- Cranes that pick up scrap metal
You can change how strong an electromagnet is. You do this by changing the electric current or the number of wire coils. This makes them important for technology and industry.
Temporary Magnets
Temporary magnets act like magnets only when they are near a strong magnetic field or another magnet. They lose their magnetism quickly after you take away the field. Paperclips and iron nails can become temporary magnets if you touch them with a strong magnet. Their atoms line up for a short time, but soon go back to normal.
Temporary magnets have low coercivity, so they cannot keep their magnetic state. You use them when you need a weak magnet that does not last long. They help in science experiments and some simple machines.
Note: Temporary magnets are not the same as permanent magnets or electromagnets. They need an outside force to become magnetic and cannot stay magnetic for long.
When you learn about the types of magnets, you can better understand how magnets affect the world around you.
Magnet Strength and Loss
What Affects Strength
Some magnets feel stronger than others. Many things decide how strong a magnet is:
- Material Composition: The kind of material is very important. Neodymium magnets are much stronger than ceramic or Alnico magnets. Their atoms line up better.
- Size and Shape: Bigger magnets have stronger magnetic fields. The shape matters too. Disc or cylinder shapes can focus the magnetic force.
- Distance: The closer you are to a magnet, the stronger it pulls. The force gets weaker as you move away.
- Temperature: Heat can make a magnet weaker. High heat makes atoms move more. This causes magnetic domains to lose their order. Each magnet type has a Curie temperature. If you heat a magnet past this, it can lose its strength forever.
- Orientation: The way you place a magnet changes how strong it feels. Magnetic field lines go from north to south pole. The alignment can change the force you feel.
Tip: To keep magnets strong, store them in a cool place. Put opposite poles together or use a keeper bar.
Here is a table that shows how temperature changes magnet strength:
| Magnet Type | Temperature Effect on Strength | Max Operating Temp | Notes |
|---|---|---|---|
| Neodymium (NdFeB) | Loses strength above 80°C (standard); high grades up to 200°C | 80–200°C | Very strong, but sensitive to heat |
| Samarium Cobalt | Keeps strength up to 350°C | Up to 350°C | Good for high-heat uses |
| Alnico | Stable up to 900°C | 450–900°C | Best for high temperatures |
| Ferrite (Ceramic) | Works up to 300°C; loses strength below -40°C | Up to 300°C | Good for many uses, but weaker than others |
Losing Magnetism
Magnets can get weaker over time or if you treat them badly. Here are the main reasons:
- Heat: Heating a magnet above its Curie temperature makes it lose magnetism forever.
- Physical Damage: Dropping or hitting a magnet can shake the atoms out of order. This makes it weaker.
- Corrosion: Rust or damage can break down the magnet. This causes the magnetic domains to lose their order.
- Opposing Magnetic Fields: Putting a magnet near a strong, opposite field can erase its power.
- Improper Storage: Storing magnets with like poles together can make them lose strength faster. Use a keeper bar or store with opposite poles together to help them last longer.
- Time: Most new magnets lose only a little strength over many years. But a small amount of loss can still happen.
Note: To help magnets last, keep them away from heat. Store them the right way and do not drop them.
You know magnets work because of atoms and electrons. The table below shows how atomic structure affects magnetism in things you use every day:
| Key Concept | Description |
|---|---|
| Electron configuration | Unpaired electrons cause magnetism. |
| Magnetic domains | Groups of atoms line up to make strong magnets. |
| Ferromagnetic materials | Iron, cobalt, and nickel can become permanent magnets. |
Magnets help power many things, like motors and medical tools.
- Look for magnets in your toys or headphones.
- Learning about magnets can make you curious and help you find out more about science and engineering!
FAQ
What happens if you cut a magnet in half?
You get two smaller magnets. Each piece forms its own north and south pole. No matter how many times you cut a magnet, you always end up with two poles on each piece.
Can magnets lose their strength over time?
Yes, magnets can get weaker. Heat, dropping, or storing them the wrong way can cause this. If you keep magnets cool and handle them gently, they stay strong longer.
Why do only some metals stick to magnets?
Only metals with unpaired electrons, like iron, cobalt, and nickel, stick to magnets. These metals have atoms that line up and create strong magnetic fields. Other metals do not have this property.
Are magnets safe to use around electronics?
Magnets can damage some electronics. Strong magnets may erase data on credit cards or hard drives. Keep magnets away from computers, phones, and cards to avoid problems.
How can you make a weak magnet stronger?
You can stroke the weak magnet with a strong one, always in the same direction. Cooling the magnet and storing it with opposite poles together also helps. Avoid heat and dropping to keep magnets strong.