^Magnetism occurs as naturally and artificial
Magnetism exist as natural or artificial magnets
1. Natural magnet occurs naturally as a piece of stone known as lodestone a dark coloured are of iron found naturally.
And it possesses the following properties.
- Its attract piece of iron towards itself.
- It sets in a fixed direction (North – south) when freely suspended.
2. ARTIFICIAL MAGNET
An artificial magnet is magnet obtained by:
i. Robbing a piece of iron with lodestone or already made magnet until it acquires the properties similar to that of lodestone.
ii. Electrical method.
GENERAL PROPERTIES OF A MAGNET:
i. They attract piece of metal such as iron. Nickel, steel, cobalt etc.
ii. They have the ability to repulse metals of like polarity, while, unlike poles attract.
iii. They set in a north – south direction when freely suspended.
The magnet poles are the two points at the end of a magnets bar in which the magnetic properties are most pronounced,
METHOD OF IDENTIFICATION OF POLARITY:
By free suspension: when a magnetic bar is freely suspended, one end appears to be set in the north direction, and as such marked North Pole (identity as south –seeking pole).
MAGNETIC AND NON MAGNETIC MATERIALS:
Non magnetic materials are classified in to two:
1. Diamagnetic materials: a diamagnetic material usually has its orbital electrons slightly disturb in the presence of a magnetic field.
2. Paramagnetic material: are materials that increase their magnetic strength as a result of the presence of a magnetic field which tends to partially align.
3. TEMPORARY AND PERMANENTS MAGNETS:
i. A temporary magnets one which can be as the easy magnetized and easily demagnetized as soon as the magneting source is removed e. g cots iron.
ii. A permanents magnet is one which is slightly difficult to magnetizing but once magnetized, it is not easy to magnetize e.g steed, alloys etc.
Magnetic field is the region or space around a magnetic where it force of attraction and repulsion can be felt
Magnetic potential at a point is a measure of the work done in moving a north pole from infirmly to that point under consideration.
MOLECULAR THEORY OF MAGNETISM:
According to Wilhelm Weber, every magnetic material made up of molecular magnets (or dipoles)
Irrespective of how small the size which the magnets is broken into.
Magnetics keepers are small piece of soft –iron used to protect bar magnets from self demagnetization with time.
MAGNETIC DECLINATION OF VARIATION:
Magnetic direction or variation is the angle between the magnetic and geographical meridians at the place concerned.
ANGLE OF DIP OR INCLINATION:
This is the angle between the axis of a freely suspended magnet and the horizontal.