1. Chapter 15 Lesson 3 Pages F30 – F35
Magnets
Chapter 15 Lesson 3
Pages F30 – F35

2. Objectives Observe the magnetic fields of different magnets
Recognize magnetism as a force that acts between magnets and magnetic objects
Understand how electromagnets are made and how they work

3. Main Idea
Magnetism comes from a special alignment of an atom’s electrons as found in iron and many other metals. Electric currents also create magnetic fields.

4. Prehistoric Peoples
Magnetism discovered when prehistoric peoples found magnetic rocks called LODESTONES
Lodestones are mostly iron, and attract or repel certain metals

5. Today
Scientists know that magnetism is a force created by the motion of electrons in atoms.
Moving electrons produce magnetic fields
Electrons aligned in the same direction, fields around them combine to create a strong magnet

6. Nonmagnetic
Atoms of paper and other nonmagnetic materials also have tiny magnetic fields.
However, they all point in different directions canceling each other out and do not create a strong magnetic field.
See page F30 for picture

7. Magnets Atoms are aligned in the same directions
This forms two regions called poles
Named North and South

8. Poles All magnets have two poles, even if broke in half
Bring the like poles together  repel each other
Bring the opposite poles together  attract
Each pole is also attracted to earth’s poles

9. Making magnets
Bring a permanent magnet close to a magnetic material will temporarily change the alignment of its atoms.
Example: Rub a magnet along an iron nail and the iron nail will become a magnet temporarily.

10. Another way You can also use an electric current
Electrons moving through a wire create a magnetic field around the wire
Placing magnetic materials in this field will realign their atoms.
This is called ELECTROMAGNET
See page F32 (do class demonstration)

11. Auroras
Auroras Borealis – also called the northern lights, is seen at night in the north
Looks like ribbons of green or red
Why? The earth is a giant magnet
Fast electrons collide with atoms and molecules of oxygen and nitrogen that make up Earth’s atmosphere
They are attracted by the poles

12. Auroras Cont.
Auroras are produced in Earth’s polar regions because this is where the magnetic field is strongest.
Color depends on gas hit by electrons.
Electrons come from the sun.

13. The End