Magnetism The properties and interactions of magnets

Magnetism What 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 Forces Magnets 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 Field Strongest close to the magnet and weaker far away Represented by magnetic field lines Has a direction

Magnetic Poles All 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 Direction Compass 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 Materials Only iron, cobalt, or nickel are attracted to magnets or made into permanent magnets Electrons have magnetic properties.

Magnetic Domains In 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 Magnet Made by placing a magnetic material in a strong magnetic field. The magnetic field causes the magnetic domains to line up.

Loss of Magnetism Heat ◦ Causes atoms in the magnet to move faster Dropping the magnet