Magnetism is an invisible force or field that causes objects to attract or repel one another. The motion of electrons or electric charges causes the force of magnetism. Everything in our universe is made up of atoms. Each atom includes electrons, which are particles that carry electric charges. Electrons spin around the atom’s center called the nucleus.
Most materials are not magnetic because the same number of electrons spin in one direction as in the other, so their magnetism is canceled. However, most electrons spin in the same direction in magnetic materials, such as metals like iron, cobalt, and nickel. These materials are not magnets but will become magnetized when an existing magnet comes close to it, i.e., it enters the magnet’s magnetic field. A magnetic field is an area around a magnet with a magnetic force.
Types of magnets
Permanent magnets
Permanent magnets are always magnetic. They produce a consistent magnetic field due to their internal structure. An example of a permanent magnet is the magnet in your fridge door. It is always magnetic, so the door closes every time you push it closed.
Temporary magnets
Temporary magnets only become magnetic when they are close to a permanent magnet and lose their magnetism when not near the permanent magnet. Examples of temporary magnets include paperclips and nails, which can be picked up with a strong interest.
If you place a piece of iron next to a magnet and rub it along it, the atoms in the iron will line up so that the iron becomes a magnet. All the atoms lining up in the same direction cause a force to be produced, creating a magnetic field.
Another type of temporary magnet is called an electromagnet. An electromagnet is created when a material is magnetized due to an electric current. For example, a magnetic field is produced when electricity runs through a coil of wire. This electric field disappears when the electric current is turned off. An electromagnet is normally made of a piece of iron with a coil of wire around it. They can have different strengths of magnetism and are commonly used in everyday items like doorbells and motors.
All magnets have north and south poles. As a result, the same poles repel each other, and opposite poles attract.
- North – North = repel
- South-South = repel
- North – South = attract
- South – North = attract
Examples of magnetic and non-magnetic materials
Non-magnetic
- Cloth
- Paper
- Plastic
- Gold
- Silver
- Copper
- Wood
- Glass
Magnetic
- Iron
- Cobalt
- Nickel
- Stainless steel
- Rare earth metals e.g. samarium, dysprosium and neodymium.
- The Earth!
Our planet Earth is a magnet because there are electric currents in the molten iron core. This hot liquid iron is constantly moving, creating a magnetic field. So the Earth is like a very big, weak magnet with a north and south pole. It is why compasses point north! The compass needle is a magnetized metal that aligns with the Earth’s magnetic field.
