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

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

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.

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

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

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

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

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

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.

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)

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

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.

The End