Magnets, Magnetism & Electromagnetism

Magnets and Magnetic Fields Magnets can be classified as ferromagnets, electromagnets, temporary magnets, and permanent magnets. A material is magnetic if its domains line up Magnetic materials include iron, nickel, and cobalt Every magnet is surrounded by a magnetic field. The shape of the field can be shown with magnetic field lines.

PERMANENT ELECTROMAGNET TEMPORARY FERROMAGNET

Domains – regions of aligned electron spins

Making Magnet Need a ferromagnetic material Need to align the domains Can be done with electricity Can be done with the force field of another magnet

Ferromagnetic Materials

Magnetic Field – Lines of Force

Magnets and Magnetic Poles All magnets have two poles. The north pole will always point to the north if allowed to rotate freely. The other pole is called the south pole. Like magnetic poles repel each other. Opposite magnetic poles attract.

Lines of Force – Attracting Magnets

Lines of Force – Repelling Magnets

Electromagnetism Pushing a magnet through a coil of wires generates electric current

This coil of wires is called a SOLENOID Electromagnetism Flowing electricity creates a magnetic force field This coil of wires is called a SOLENOID

Electromagnetism Add an iron core and you create an electromagnet

Advantages of Electromagnets Can be turned off and on Can be made stronger Polarity can be reversed