Magnets Magnets got their name from a region in Greece formerly known as Magnesia.  The first naturally occurring magnets, lodestones, were found here almost 3000 years ago.

Magnets Naturally occurring magnets (lodestones) are called permanent magnets.  Permanent magnets are magnetic all the time.

Magnets Permanent magnets can be used to magnetize other pieces of iron. Magnetic items are classified one of two ways: 1) Magnetically hard – Hard to magnetize and does not lose magnetism easily 2) Magnetically soft – Easily magnetized and easily loses magnetism

Magnetic Forces Magnets exert magnetic forces on each other.  Like Poles repel  Opposite poles attract The closer the magnets are to each other, the more intense the force (Attractive or repulsive).

Magnetic Fields What is a magnetic field?  A magnetic field is a region where a magnetic force can be detected. MAGNETIC FIELDS  All magnets produce magnetic fields  Some magnetic fields are stronger than others

Magnetic Fields MAGNETIC FIELDS STRENGTH DEPENDS ON TWO THINGS: 1) The material from which the magnet is made 2) The degree of magnetization

Earth’s Magnetic Field Earth’s magnetic field is like that of a bar magnet  It has both direction and strength  It has changed direction throughout geologic time

Earth’s Magnetic Field Earth’s magnetic poles are not the same as its geographic poles

What can track magnetic Fields? Compasses can track magnetic fields. A compass is a magnet suspended on top of a pivot so that the magnet can rotate freely.

Magnetic Fields Atoms have electrons that are in constant motion. The moving charges constitute a tiny current and produce a magnetic field. Every spinning electron is a tiny magnet. An electron pair spinning in the same direction make up a stronger magnet. Electrons spinning in opposite directions work against one another.

Magnetic Fields Iron triad – Fe, Co, and Ni are the only magnetic elements.