1. What is Magnetism? 23-1

2. The compass was an important development for navigation and exploration, especially at sea. Early Uses

3. Magnets attract objects made of iron or steel, such as nails and paper clips. Magnets also can attract or repel other magnets. Magnets

4. Every magnet has two ends, or poles. One end is called the north pole and the other is the south pole. Magnets Click image to view movie.

5. Two north poles or two south poles repel each other. North and south magnetic poles are attracted to each other. Magnets

6. This magnetic force is exerted through a magnetic field. The Magnetic Field Curved lines that start on one pole and end on the other are called magnetic field lines.

7. Where the magnetic field lines are close together, the field is strong. Field lines that curve toward each other show attraction. The Magnetic Field

8. Inside every magnet are moving charges. All atoms contain negatively charged particles called electrons. Making Magnetic Fields Not only do these electrons swarm around the nucleus of an atom, they also spin.

9. Because of its movement, each electron produces a magnetic field. Making Magnetic Fields A group of atoms, with their fields pointing in the same direction, is called a magnetic domain.

10. Microscopic sections of iron and steel act as tiny magnets. Making Magnetic Fields Normally, these domains are oriented randomly and their magnetic fields cancel each other.

11. When a strong magnet is brought near the material, the domains line up, and their magnetic fields add together. Making Magnetic Fields

12. Earth has a magnetic field. Earth's Magnetic Field The region of space affected by Earth's magnetic field is called the magnetosphere.

13. Honeybees, rainbow trout, and homing pigeons take advantage of magnetism to find their way. Nature's Magnets These animals and other have tiny pieces of magnetite in their bodies.

14. Earth's magnetic poles do not stay in one place. Earth's Changing Magnetic Field The magnetic pole in the north today is in a different place from where it was 20 years ago.

15. A compass needle is a small bar magnet with a north and south magnetic pole. The Compass In a magnetic field, a compass needle rotates until it is aligned with the magnetic field line at its location.