Artificial magnets

Natural Magnets

A natural magnet is a magnet that occurs naturally in nature. All natural magnets are permanent magnets, meaning they will never lose their magnetic power.
Natural magnets can be found in sandy deposits in various parts of the world. The strongest natural magnet material is lodestone, also called magnetite. This mineral is black in color and very shiny when polished. The lodestone was actually used in the very first compasses ever made. Because natural magnets are permanent magnets, if lodestone is allowed to freely spin, its north pole will always align itself with the Earth's geographic north pole.

Causes of Magnetism

Whether a material is magnetic or not depends on the material’s atoms.
In material such as iron, nickel, and colbalt, groups of atoms are in tiny areas called domains.
The arrangement of domains in an object determines whether the object is magnetic.
When domains move the magnet is demagnetized or looses its magnetic properties.

There are other minerals that are natural magnets, but they are weak magnets so they won't be able to lift too much metal. Some of these are pyrrhotite, ferrite and columbite.

pyrrhotite

ferrite

columbite

Artificial Magnets

When magnets are made by people, they are called artificial magnets. It's these magnets that are on your refrigerator door, and they have extra-strong magnetic power, like those really tiny super-strong magnets that you can buy from toy or science stores.

Artificial Magnets

Artificial or man made magnets are made by magnetising:
Iron
Nickel
Cobalt
Alloys of the above

The Poles

Magnets are strongest at their 2 ends called the “north pole” and the “south pole”.








Like Poles Repel and Unlike Poles Attract.

Two types of artificial magnets: temporary and permanent.

Temporary

Permanent

Temporary: When charged particles move through space, they induce a magnetic field (Electromagnets).
Permanent: Electrons have an intrinsic magnetic field that may add together in certain matter to create a magnetic field (Speakers).

A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. 

An everyday example is a refrigerator magnet used to hold notes on a refrigerator door.

A magnet can be created by magnetizing a piece of iron or steel or by using electricity to make an electromagnet.

The loudspeakers in your radio, television or stereo system consists of a permanent magnet surrounding an electromagnet that is attached to the loudspeaker membrane or cone.

By varying the electric current through the wires around the electromagnet, the speaker cone moves back and forth.

The resulting vibration of the speaker cone will create sound waves, including that from voice and music.

Maglev Trains

Magnetic + Levitation = maglev


Maglev vehicles “float” over an electromagnetically powered fixed steel guideway and are propelled by the current with no motors, wheels, moving parts or additional energy sources. The system is environmentally friendly, energy efficient and runs in all weather conditions.

http://dsc.discovery.com/videos/extreme-engineering-season-1-shorts-maglev-train.html

Uses of Magnets

Transformers
PhonesComputer disc drives (hard and floppy)
VCR and cassette tape
Credit cards
Speakers
Motors (Both AC and DC)
Speed sensors
Solenoids for relays, valves, etc.
Magnetos (piston engine aircraft)

Key Ideas

All magnets have North and South Poles
Magnetic field lines originate in the North and end at the south pole.
Magnetic field lines do not cross.
Magnetism exists at the atomic level.
Magnetism is the result of moving charges.
Some magnets are temporary while others are permanent.
Types of Magnetism.
Ferromagnetism.
Paramagnetism.
Diamagnetism.