MAGNETISM

HISTORY

More than 2000 years ago – Greeks discovered a rock that was attracted to materials that contained iron.

MAGNETITE was this rock

FIRST USE

LODESTONE – made from magnetite (Fe3O4)

Used to make a compass used by ancient Greek & Chinese

MAGNETISM

The ability of a substance to attract iron

Magnets have magnetic poles. There are two poles:1) North Seeking Pole (NORTH)2) South Seeking Pole (SOUTH)

EARTH IS A MAGNET!

MAGNETIC FIELD

The region around a magnet where the magnetic force acts & is composed of lines of force.

POLE INTERACTIONS

Opposite poles = force of attraction

Like poles = force of repulsion

What does that look like?

FORCE OF ATTRACTION

CAN YOU SEE THE LINES OF FORCE?

FORCE OF REPULSION

REPULSION = PUSHES AWAY

ATTRACT AND REPEL!

REPEL!

ATTRACT!

SUMMARY

EVERYDAY USES OF MAGNETS

MORE USES

MORE USES!

This is a MRI machine.

MRI stands for:Magnetic Resonance

Imaging

More USES!

Types of Magnets

Temporary – made by induction, magnetism that only occurs in the presence of a magnetic field

Permanent – simply b/c some materials are SO influenced by magnetic fields, they become magnets themselves (Fe, Ni, Co)

MAGNETIC DOMAINS

Alignment of particles in the material can determinewhether it will be magnetic or not.

MAGNETIZING A NAIL(INDUCTION)