How Do Magnets Work? — For Kids

Elementary Middle School

A magnet pulls some things to it

A magnet is a metal.

It can attract certain other metals. Attract means pull to it.

Magnetism is the force made by magnets.

Magnetism does the holding when a magnet holds a note on a refrigerator door.

The magnetic force is invisible. You cannot see it.

A magnet can even lift a paper clip without touching it.

Every magnet has two poles

A magnet has two ends. The ends are called poles.

The poles are where the magnetic effects are strongest.

One pole is the north pole. One pole is the south pole.

Same poles push away. Different poles pull together.

Poles that are alike push away from each other. That is called repel.

North and north repel. South and south repel.

Poles that are different pull to each other. That is called attract.

North and south attract.

What do magnets stick to?

Magnets are attracted to things that contain metals such as iron.

Refrigerator doors contain metals such as iron. That is why magnets hold notes there.

A paper clip can be picked up by a magnet, too.

But a magnet attracts only certain metals. It does not attract everything.

Earth is like a big magnet

In a sense, yes — Earth is a magnet, too.

Earth's core makes its own magnetic field.

Earth has a protective magnetic field around it. It shields us from most of the energy and small particles the Sun sends our way.

This giant bubble of magnetism around Earth is called the magnetosphere.

It pushes away most of the material sweeping toward us from the Sun.

How does a compass work?

The needle of a compass is a small magnet.

The needle can turn freely.

Earth's magnetic field moves the needle. The needle lines up with the field.

The north end of the needle points in the general direction of the geographic North Pole.

The south end points the opposite way, toward the geographic South Pole.

Pretty lights near the poles

An aurora is a colorful light show in the sky. The Sun causes it.

Some particles from the Sun travel down Earth's magnetic field lines at the north and south poles.

Then they meet gases in our air. That makes beautiful displays of light.

Near the North Pole, the lights are called the northern lights.

Near the South Pole, they are called the southern lights.

What magnetism is

Magnetism is the force produced by magnets.

A magnet is a metal that can attract certain other metals.

A magnetic material has a magnetic field that can attract or repel other magnetic materials.

The region around a magnet where a magnetic force can be found is called its magnetic field.

The magnetic force is an invisible force. It can act without touching: in a NASA classroom activity, a magnet lifts a paper clip, and can even make the clip stand up, without the magnet and the clip touching.

Magnetism is also an important force in nature. It can move hot gases in stars, and in the space around Earth.

Poles: where a magnet is strongest

Poles are the two areas of a magnet where the magnetic effects are strongest.

The poles are generally called the north pole and the south pole.

A magnet has two ends, or poles, that will attract or repel the poles of another magnet.

Poles that are alike — both north or both south — will repel each other.

Poles that are different — one north and one south — will attract each other.

What magnets attract

Magnets are attracted to items which contain metals such as iron.

That is why simple magnets hold notes on refrigerator doors, which contain metals such as iron.

Note the word "certain." A magnet attracts certain other metals — not every material, and not every metal sample behaves the same way. Testing which samples a magnet attracts is itself a NASA classroom activity.

Earth is a magnet — in a sense

The U.S. Geological Survey answers the question "Is the Earth a magnet?" this way: in a sense, yes.

Earth is made of layers with different chemical compositions and different physical properties.

The crust of Earth has some permanent magnetization.

Earth's core generates its own magnetic field. That field sustains the main part of the field we measure at the surface.

But Earth's core is not permanently magnetized. Its temperature is several thousand degrees Celsius.

Permanent magnetization cannot occur at temperatures above about 650 degrees Celsius (1,200 degrees Fahrenheit). At those temperatures, the thermal motion of atoms is too vigorous to maintain the ordered orientations needed for permanent magnetization.

Earth's magnetic field is generated by the convective motion of charged, molten iron, far below the surface in Earth's outer core.

Earth's field lines and the magnetosphere

Earth, acting just like a very large magnet, produces invisible lines of force, called magnetic field lines.

Earth's field lines start near the South Pole of Earth, curve around in space, and converge again near the North Pole. That pattern is called a dipole.

Extending beyond Earth's polar regions, far out into space, these field lines form the magnetosphere.

A magnetosphere is the region around a planet dominated by the planet's magnetic field.

Earth has the strongest magnetosphere of all the rocky planets. It is a vast, comet-shaped bubble, and it has played a crucial role in our planet's habitability.

The magnetosphere shields our home planet from solar and cosmic particle radiation. It also shields Earth from erosion of the atmosphere by the solar wind — the constant flow of charged particles streaming off the Sun.

The sun-facing side of the magnetosphere extends about six to 10 times the radius of Earth. The side facing away from the Sun stretches out into an immense magnetotail. The magnetotail can measure hundreds of Earth radii, far past the Moon's orbit at 60 Earth radii.

Without the magnetosphere, the relentless action of solar particles could strip Earth of its protective layers, which shield us from the Sun's ultraviolet radiation.

Mars shows the contrast. Mars lost its magnetosphere about 4.2 billion years ago, and the solar wind is thought to have stripped away most of Mars' atmosphere.

Other planets are magnetized, too. Jupiter, Saturn, Uranus, and Neptune are magnetized even more intensely than Earth. Mars has a weak magnetic field, Mercury has a small magnetosphere, and Venus appears to be unmagnetized.

Compasses and declination

The needle of a compass is a small magnet, one that is allowed to pivot freely.

When the needle experiences a magnetic field — from a nearby magnet or from Earth's magnetic field — it moves. The needle aligns itself with that magnetic field.

The north end of the compass needle is simply the north end of the magnet. It points in the general direction of the geographic north pole. The south end points in the opposite direction, toward the geographic southern pole.

At most places on Earth's surface, the compass does not point exactly toward geographic north.

The deviation of the compass from true north is an angle called declination, or magnetic declination. It varies with both geographic location and time. At very high latitudes, the compass can even point south.

Declination happens because the geomagnetic field is complex. The field is not perfectly symmetrical, and the dipole itself is not perfectly aligned with the rotational axis of Earth.

A compass can also be affected by local interference, like a nearby electrical system, and by local magnetization of Earth's crust, particularly near large igneous or volcanic rock deposits.

Animals, auroras, and the magnetic field

Some animals use Earth's magnetic field. There is evidence that sea turtles and salmon can sense Earth's magnetic field — although probably not consciously — and use this sense for navigation.

Scientists believe salmon navigate by using Earth's magnetic field like a compass.

The field also shapes auroras. When a solar storm comes toward us, some of the energy and small particles can travel down the magnetic field lines at the north and south poles into Earth's atmosphere.

There, the particles interact with gases in our atmosphere, resulting in beautiful displays of light in the sky. Oxygen gives off green and red light. Nitrogen glows blue and purple.

Auroras are not just an Earth event. If a planet has an atmosphere and a magnetic field, it probably has auroras. We have seen amazing auroras on Jupiter and Saturn.

Words to know

• Magnet: a metal that can attract certain other metals.
• Magnetism: the force produced by magnets. It is an invisible force.
• Magnetic field: the region around a magnet where a magnetic force can be found. A magnetic material has a magnetic field that can attract or repel other magnetic materials.
• Pole: one of the two areas of a magnet where the magnetic effects are strongest. The poles are called the north pole and the south pole.
• Attract: to pull toward. Poles that are different — one north, one south — attract each other.
• Repel: to push away. Poles that are alike — both north or both south — repel each other.
• Compass: a tool whose needle is a small magnet that is allowed to pivot freely. The needle aligns with a magnetic field, and its north end points in the general direction of the geographic north pole.
• Magnetosphere: the region around a planet dominated by the planet's magnetic field. Earth's magnetic field is also called its magnetosphere, and it shields Earth from most of the Sun's energy and particles.
• Solar wind: the constant flow of charged particles streaming off the Sun.
• Declination: the angle between where a compass points and true north. At most places, a compass does not point exactly toward geographic north, and that difference is the declination.
• Aurora: a colorful light show in the sky caused by the Sun, when particles from the Sun interact with gases in our atmosphere. Near the North Pole it is called the northern lights; near the South Pole, the southern lights.