Magnets and Magnetic Forces

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: Magnetically hard – Hard to magnetize and does not lose magnetism easily 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? MAGNETIC FIELDS 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 FIELD STRENGTH DEPENDS ON TWO THINGS: The material from which the magnet is made The degree of magnetization

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 – Iron, Cobalt, and Nickel are the only magnetic elements.

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.