1. Magnets and Magnetism Did you know? More than 2000 years ago, the Greeks discovered a mineral that attracted objects containing iron. Because this mineral was found in a part of Turkey called Magnesia, the Greeks called it Magnetite. Today any material that attracts iron is called a magnet.Did you know? More than 2000 years ago, the Greeks discovered a mineral that attracted objects containing iron. Because this mineral was found in a part of Turkey called Magnesia, the Greeks called it Magnetite. Today any material that attracts iron is called a magnet.

2. Magnets and Magnetism The magnetic effects of a magnet are NOT evenly distributed through the magnet.The magnetic effects of a magnet are NOT evenly distributed through the magnet. The parts of a magnet where the magnetic effects are strongest are called the poles.The parts of a magnet where the magnetic effects are strongest are called the poles.

3. Magnets and Magnetism If you attach a magnet to a string so that the magnet is free to rotate, you will see that one end of the magnet always ends up pointing north and the other end will point to the south.If you attach a magnet to a string so that the magnet is free to rotate, you will see that one end of the magnet always ends up pointing north and the other end will point to the south. Magnetic poles always occur in pairs, you will never find a magnet with only a north pole or only a south pole.Magnetic poles always occur in pairs, you will never find a magnet with only a north pole or only a south pole.

4. Magnets and Magnetism The force of attraction or repulsion between the poles of magnets is called the magnetic force.The force of attraction or repulsion between the poles of magnets is called the magnetic force. The magnetic force depends on how the poles of the magnets line up.The magnetic force depends on how the poles of the magnets line up.

5. Magnets and Magnetism A magnetic field exists in the region around a magnet in which magnetic forces can act.

6. Magnets and Magnetism Magnetic field lines are close together where the magnetic force is strongest, andMagnetic field lines are close together where the magnetic force is strongest, and farther away farther away where the where the force is weaker. force is weaker.

7. Magnets and Magnetism Some materials are magnetic, and some are not. What causes the difference?Some materials are magnetic, and some are not. What causes the difference? Whether a material is magnetic depends on the atoms in the material.Whether a material is magnetic depends on the atoms in the material.

8. Magnets and Magnetism All matter is composed of atoms that include protons, electrons and neutrons. Moving electrons produce magnetic fields that can give an atom a north and a south pole.All matter is composed of atoms that include protons, electrons and neutrons. Moving electrons produce magnetic fields that can give an atom a north and a south pole. In most materials, the magnetic fields of individual atoms cancel each other out.In most materials, the magnetic fields of individual atoms cancel each other out.

9. Magnets and Magnetism But in some materials, the atoms in a magnetic domain are arranged so that the north and south poles of all the atoms line up and create a strong magnetic field.But in some materials, the atoms in a magnetic domain are arranged so that the north and south poles of all the atoms line up and create a strong magnetic field.

10. Magnets and Magnetism Types of magnets: Ferromagnets – magnets made with metals Electromagnets – produced by an electric current. Temporary magnets – made from materials that are easy to magnetize, but they lose their magnetization easily too. Permanent magnets – difficult to magnetize, but retain their magnetic properties better.

11. Magnets and Magnetism Did you know? In 1600, English physician William Gilbert suggested that magnets point to the north because Earth itself is one GIANT magnet.

12. Magnets and Magnetism Although you can think of Earth as have a giant bar magnet in the center, there really isn’t a magnet there.Although you can think of Earth as have a giant bar magnet in the center, there really isn’t a magnet there. The temperature of Earth’s core is so high that atoms in it move too violently to remain in domains.The temperature of Earth’s core is so high that atoms in it move too violently to remain in domains.

13. Magnets and Magnetism Earth’s magnetic field is produced by the movement of charges in the Earth’s core.Earth’s magnetic field is produced by the movement of charges in the Earth’s core.

14. Magnets and Magnetism One of the most spectacular effects caused by the Earth’s magnetic field is a curtain of light called an aurora.One of the most spectacular effects caused by the Earth’s magnetic field is a curtain of light called an aurora.

15. Magnets and Magnetism An aurora is formed when charged particles from the sun interact with atoms in Earth’s atmosphere. We see the interactions at Earth’s magnetic field.