Magnet facts for kids
A magnet is a special object or material that creates an invisible area around it called a magnetic field. This field is what gives a magnet its amazing power. It can pull on certain metals like iron, steel, nickel, and cobalt. Magnets can also attract or push away other magnets.
There are two main types of magnets. A permanent magnet is always magnetic. Think of the refrigerator magnet holding your drawings! These magnets are made from materials that stay magnetized on their own. These materials are called ferromagnetic (or ferrimagnetic). Examples include iron, nickel, cobalt, and some special rare-earth metals. Even some natural rocks, like lodestone, are permanent magnets. While these are the strongest, all materials react a little bit to a magnetic field.
Some materials are "magnetically soft." They can become magnets easily but lose their magnetism just as quickly. Other materials are "magnetically hard." These are used to make permanent magnets. They are specially treated to keep their magnetic power for a long time. The strength of a magnet depends on how hard it is to demagnetize.
An electromagnet is different. It's usually a coil of wire that becomes a magnet only when electric current flows through it. When the current stops, it loses its magnetism. Often, this wire is wrapped around a piece of "soft" metal, like mild steel. This makes the electromagnet much stronger.
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How Magnets Were Discovered and Developed
People first learned about magnets from lodestones. These are natural rocks, a type of magnetite, that are already magnetic. The word "magnet" comes from an ancient Greek word. It means "stone from Magnesia," a place in Turkey where these rocks were found.
Ancient people noticed that lodestones could attract iron. If you hung a lodestone so it could spin, it would always point in the same direction. This was the very first magnetic compass! Descriptions of magnets go back about 2,500 years in places like Anatolia, India, and China.
In China, around the 11th century, people found a way to make iron permanently magnetic. They would heat iron until it was red hot, then cool it while it was lined up with Earth's magnetic field. This discovery helped create the navigational compass, which was used for sailing by the 12th and 13th centuries.
Later, in 1743, Daniel Bernoulli invented the horseshoe magnet. This shape helped magnets stay strong for longer.
A big breakthrough happened in 1820. A scientist named Hans Christian Ørsted found that electric current could move a compass needle. This showed a connection between electricity and magnetism! Soon after, André-Marie Ampère discovered that electricity could magnetize iron.
This led to William Sturgeon creating the first electromagnet in 1824. Then, Joseph Henry made electromagnets even stronger and more practical in the 1830s. He even built a machine that could lift heavy ore using an electromagnet.
How Magnets Work
Understanding the Magnetic Field
Every magnet creates an invisible area around it called a magnetic field. You can't see it, but you can see its effects! If you sprinkle iron filings near a magnet, they will line up along the field lines. This shows the direction and strength of the magnetic field. The stronger the field, the more strongly it pulls on magnetic materials.
Magnetic Poles: North and South
Every magnet has two ends, called poles. One is the North pole, and the other is the South pole.
- If you hang a magnet freely, its North pole will point towards Earth's North Magnetic Pole.
- Remember, opposite poles attract! So, a North pole attracts a South pole.
- Similar poles repel each other. A North pole pushes away another North pole, and a South pole pushes away another South pole.
- You can't have a magnet with only one pole. If you break a bar magnet in half, you'll just get two smaller magnets, each with its own North and South pole!
- Scientists imagine invisible lines of force coming out of the North pole and going into the South pole.
Different Types of Magnetic Materials
Not all materials react to magnets in the same way. There are several types of magnetism:
- Ferromagnetic materials are the ones we usually think of as magnetic. They are strongly attracted to magnets. These include iron, nickel, and cobalt. They are also the only materials that can become permanent magnets themselves. Ferrimagnetic materials, like magnetite (lodestone), are similar but a bit weaker.
- Paramagnetic materials are very weakly attracted to magnets. This attraction is so tiny you usually need special tools to notice it. Examples include platinum, aluminum, and oxygen.
- Diamagnetic materials are actually repelled by magnets, but even more weakly than paramagnetic materials are attracted. Most everyday things, like water, plastic, carbon, and copper, are diamagnetic. You can't feel this repulsion with a normal magnet. However, with super strong superconducting magnets, scientists can even make objects like lead or even a mouse float in mid-air!
Everyday Uses for Magnets
Magnets are everywhere! They make many technologies possible:
- Recording Information: Old VHS tapes and audio cassettes use magnetic tape to store video and sound. Computer floppy disks and hard disks also record data on magnetic coatings.
- Cards: Credit, debit, and automatic teller machine (ATM) cards have a magnetic strip. This strip holds your account information.
- Old TVs and Monitors: Older televisions and large computer screens used electromagnets. These guided electrons to create the images you saw.
- Sensors: Magnets are used in sensors to detect movement, position, or how far something has moved.
- Speakers and Microphones: Most speakers use a permanent magnet and a coil of wire. Electric signals make the coil move, creating sound. Microphones work in reverse, turning sound vibrations into electrical signals.
- Electric Guitars: These guitars use magnetic pickups. They turn the vibrations of the strings into electric currents that can be made louder.
- Motors and Generators: Electric motors use magnets to turn electrical energy into movement. Generators do the opposite, turning movement into electricity.
- Medicine: Hospitals use powerful magnets in magnetic resonance imaging (MRI) machines. These machines help doctors see inside the body without surgery.
- Chemistry: Chemists use a technique called nuclear magnetic resonance to study different chemical compounds.
- Holding Things: Magnets are used in chucks to hold metal objects in factories. They are also in magnetic bases, magnetic clamps, and, of course, refrigerator magnets.
- Compasses: A magnetic compass has a magnetized needle that points to Earth's magnetic field, helping us find directions.
- Art and Toys: Magnets are used in fun toys like construction sets. You can also use magnetic sheets for art projects on metal surfaces.
- Picking Up Small Items: Magnetized screwdrivers can pick up tiny screws. Larger magnets can collect iron nails or staples.
- Recycling: Magnets help separate magnetic metals (like iron) from non-magnetic ones (like aluminum) in recycling centers.
- Food Safety: In food factories, magnets remove tiny metal pieces from ingredients. This protects both machines and consumers.
- Maglev Trains: Magnetic levitation trains float above the tracks using powerful electromagnets. This reduces friction and allows them to travel at very high speeds, like the record-breaking 581 km/h (361 mph) achieved by a maglev train.
- Safety Connections: Some laptop power cords use magnets. If someone trips on the cord, it safely detaches instead of pulling the laptop down. The MagSafe connection on Apple MacBooks is a good example.
Magnet Safety and Health
Magnets are generally safe, but there are a few things to know:
- Static Magnetic Fields: The magnetic fields from everyday magnets are usually not strong enough to affect human tissues. Scientists have found little evidence of health problems from these fields.
- Metal in the Body: If someone has a piece of metal inside their body, a strong external magnet could be dangerous.
- Pacemakers: People with pacemakers (devices that help regulate the heart) must be careful around strong magnetic fields. This is why they cannot have an MRI scan.
- Swallowing Magnets: Small magnets from toys can be very dangerous if swallowed. If two or more magnets are swallowed, they can attract each other inside the body, pinching or puncturing internal tissues.
- MRI Machines: MRI machines use extremely powerful magnets. Because of this, no metal objects (like oxygen tanks) are allowed in an MRI room. The strong magnetic field could pull them with great force, causing serious injury.
How to Magnetize Materials
Ferromagnetic materials can be made magnetic in a few ways:
- Heating and Cooling: The most effective method is to heat the material very hot (above its Curie temperature). Then, let it cool down while it's in a strong magnetic field. Hitting it gently as it cools also helps. This is how many permanent magnets are made.
- External Magnetic Field: Placing a material in a strong magnetic field will make it slightly magnetic, even after the field is removed. Vibrating the material can increase this effect.
- Stroking: You can stroke a material with an existing magnet. Move the magnet from one end to the other, always in the same direction.
- Electric Current: Wrapping a wire around a material and running an electric current through the wire can magnetize it. This aligns the tiny magnetic parts inside the material.
How to Demagnetize Materials
Sometimes you need to remove a magnet's power. This is called demagnetizing or degaussing:
- Heating: Heating a magnet above its Curie temperature will make it lose all its magnetism. The heat makes the tiny magnetic parts inside move randomly, destroying their alignment.
- Alternating Magnetic Field: Placing a magnet in a strong, rapidly changing magnetic field can demagnetize it. This is how commercial demagnetizers work for tools or old computer screens. Slowly pulling the magnet away or slowly reducing the field strength helps.
- Strong Reverse Field: Applying a magnetic field in the opposite direction that is strong enough can also demagnetize a magnet.
- Hammering or Jarring: Hitting or shaking a magnet can also reduce its magnetism. This disturbs the alignment of its internal magnetic parts. However, this can also damage the magnet.
Types of Permanent Magnets
Magnetic Metals
Some metals are naturally magnetic because of how their electrons are arranged. These include iron ore (like magnetite or lodestone), cobalt, and nickel. The rare earth metals gadolinium and dysprosium are also magnetic at very cold temperatures. These natural magnets were used in the earliest experiments. Today, we use these elements to create many different man-made magnets.
Composite Magnets
- Ceramic (Ferrite) Magnets: These are made from powdered iron oxide mixed with other materials like barium or strontium carbonate. They are inexpensive and can be made into many shapes. They don't rust but are brittle, like other ceramics.
- Alnico Magnets: These magnets are made by mixing aluminium, nickel, and cobalt with iron. They can be cast or molded. Alnico magnets resist rust and are tougher than ceramic magnets.
- Injection-Molded Magnets: These are a mix of plastic-like resin and magnetic powders. They can be molded into complex shapes. Their magnetic strength is usually lower, and they feel like plastic.
Flexible Magnets
Flexible magnets are made from magnetic powder mixed into a rubbery plastic. This mixture is then shaped into sheets. Powerful magnets are used to give these sheets their magnetic poles in an alternating pattern. They are not as strong as other magnets but are very flexible.
Rare-Earth Magnets
Rare-earth elements, like those in the lanthanoid family, have special electrons that create very strong magnetic fields. This makes them perfect for small, powerful magnets, even though they cost more. The most common types are samarium–cobalt and neodymium–iron–boron (NIB) magnets.
New Magnet Discoveries
Scientists are always looking for new ways to make magnets. For example, in 2011, a program called REACT (Rare Earth Alternatives in Critical Technologies) started to find new materials that don't rely on rare-earth elements. Iron nitrides are one promising material. In 2026, researchers announced new magnets made from common metals and boron. These magnets work at normal temperatures and pressures.
Magnet Costs
The cheapest permanent magnets, considering their strength, are flexible and ceramic magnets. Ferrite magnets are low-cost because they use cheap raw materials. A newer, low-cost magnet made from manganese-aluminum alloy is also becoming popular. Neodymium–iron–boron (NIB) magnets are among the strongest. They cost more per kilogram but are often cheaper overall for many uses because you need less of them.
Temperature and Magnets
Magnets are sensitive to heat. If a magnet is heated to a certain temperature, called the Curie point, it will lose all its magnetism. Even after cooling, it won't be magnetic unless it's re-magnetized. Some magnets can also break if they get too hot. Alnico magnets can handle over 540°C (1000°F), while ferrite and samarium-cobalt magnets can handle about 300°C (570°F). Neodymium magnets usually work up to about 140°C (280°F).
Electromagnets
An electromagnet is simply a wire coiled into one or more loops, called a solenoid. When electric current flows through this wire, it creates a magnetic field. This field is strongest inside and near the coil. The direction of this magnetic field can be found using the right hand rule. The strength of the electromagnet depends on how many loops of wire there are, the size of each loop, and how much current flows through the wire.
If the wire coil is wrapped around a material like cardboard, the magnetic field will be weak. But if it's wrapped around a "soft" magnetic material, like an iron nail, the magnetic field becomes hundreds or even thousands of times stronger!
Electromagnets are used in many important devices. These include particle accelerators, electric motors, cranes in junkyards, and magnetic resonance imaging (MRI) machines.
Images for kids
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Field of a cylindrical bar magnet computed accurately.
See also
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