MagnetismThe properties and interactions of magnets

MagnetismWhat You’ll learn

◦Explain how a magnet exerts a force.◦Describe the properties of temporary

and permanent magnets.◦Explain why some materials are

magnetic and some are not.

Magnetic ForcesMagnets either attract or repel.The strength of the force

between two magnets increases as magnets move closer together and decreases as the magnets move farther apart.

Magnetic FieldStrongest close to the magnet

and weaker far awayRepresented by magnetic field

linesHas a direction

Magnetic PolesAll magnets have a north pole

and south pole.Magnetic field lines always

connect the north pole and the south pole of a magnet.

Magnetic poles repel each other and unlike poles attract each other.

Magnetic Field DirectionCompass needle – small bar

magnet with a north pole and south pole

Needle rotates until it lines up the magnetic field lines

The north pole of a compass points in the direction of the magnetic field which is always away from a north magnetic pole and toward a south magnetic pole.

Magnetic MaterialsOnly iron, cobalt, or nickel are

attracted to magnets or made into permanent magnets

Electrons have magnetic properties.

Magnetic DomainsIn a metal, the poles of the

domain are arranged randomly and pointing in different directions.

If place next to a magnet, the atoms are arranged in the direction of the nearby magnetic field

Permanent MagnetMade by placing a magnetic

material in a strong magnetic field.

The magnetic field causes the magnetic domains to line up.

Loss of MagnetismHeat

◦Causes atoms in the magnet to move faster

Dropping the magnet