*Like Poles (2 North Poles Or 2 South Poles) Repel

Magnetism

2-1 Forces & Fields - Magnets are used in many of our major technologies today. Computers, TV’s, radios, telephones & more. Magnetism is a force similar to gravity, friction & inertia.

Lodestone = Magnetite – a naturally found magnetic rock named after Magnesia a region of Europe the rock was found in. Magnets were originally associated with sorcery.

One end of a magnet points North & the other points South. These 2 ends of a magnet are called magnetic poles. (North magnetic pole or South magnetic pole.)

Similar to electrical charges, magnetic poles of 2 magnets can have like poles & unlike poles.

*Like poles (2 North poles or 2 South poles) repel.

**Unlike poles (1 North & 1 South) attract.

The Earth has a magnetic field around it called the magnetosphere with layers that keep out radiation called the Van Allen radiation belts. The magnetosphere is caused by the Earth’s core being made of iron & nickel.

A magnetic field is a region around a magnet in which a magnetic force acts.

***If you break a magnet into smaller pieces, all the pieces are a complete magnet each with their own North & South poles.

2-2 Magnets

You can make a magnet out of a nonmagnet several ways. The object that can be magnetized is usually a metal. The process of making a magnet out of a nonmagnet is called induced magnetism.

Induced magnetism- magnetism that develops only on the presence of a magnetic field.

****Every atom has a tiny magnetic field around it. Metallic atoms have stronger magnetic fields.

You can align the magnetic fields of several atoms and create a domain.

*****If an object has all of its domains in line & working together it has induced magnetism & is now a magnet.

Ways to align domains

1.Introduce object to an existing magnetic field. (Rub it on a magnet).

2.Run an electrical current through it.

3. Heat it. (Rare)

4. Strike it so as to align domains. (Very rare)

Permanent magnets – magnets that keep there magnetism. Usually made of alnico. (Alloys of aluminum, nickel, & cobalt).

Electromagnet- a magnet produced by passing a current through a coil of wire wrapped around a metal core. Electromagnets can be turned on & off, but are usually stronger than permanent magnets.

2-3 Effects of magnetic fields

A magnetic field has no effect on a static charge, but it does exert a force on the wire that carries a current. The force is at a right angle (900) to the direction of the current flow.

******The right hand rule lets you see the relationship between the current flow and the magnetic force. (pg 64).

Magnets can turn current into sound by directing the current into a coil that vibrates. (Sound is vibrations!) A device that changes variations in electrical current into sound is called a loudspeaker.

Electric motors – uses electromagnets to spin a material that changes electrical energy to mechanical energy (kinetic energy of moving machine parts.)

********A commutator is a magnetic device that reverses the flow of electricity in a motor causing the motor to spin.

Induced current- an electrical current produced by using a magnet. (Don’t confuse this with induced magnetism).

Electrical generator – a device that changes kinetic mechanical energy to electricity. It uses magnets to rotate a coil in a magnetic field.

Transformer – a device that is used to raise or lower the voltage to the levels and to help supply AC (alternating current) to users.

Step up transformer – increases voltage

Step down transformer – lowers voltage