Magnetic Fields & Magnetic Poles
For historical reasons, the "end" of a magnet that points towards the North Magnetic Pole is itself called the "north pole" of the magnet, with the other end being the magnet's "south pole". Because it is unlike poles that attract, the Earth's North Magnetic Pole is therefore physically a magnetic south pole. To avoid confusion between geographic and magnetic north and south poles, the terms positive and negative are sometimes used for the poles of a magnet. The positive pole is that which seeks geographical north.
The true North Pole is one of the two points where Earth's axis of rotation meets the Earth's surface. The other point is the South Pole. So if you are heading to the true north, you should arrive the true North Pole. However, the Magnetic North Pole is the direction a camass indicates, which at one point will direct you downwards, towards the core of the earth. The Magnetic North Pole is changing, and has 'travelled' more than 1,100 km in the last century.
Measuring Magnetic Fields
There are three main unit standards for measuring the flux density.
1. The CGS method, which uses the following units: Centimetres, Grams and Seconds. The measure unit is called gauss.
2. The SI method, which uses the following: Meters, Kilograms and Seconds. The measure unit is called tesla.
3. The English method, which uses the following: Inches, Pounds and Seconds. The measure unite is called Lines/in.
The first method which uses gauss is the most popular for indicating the strength of the magnets / magnetic field in magnetic jewellery. We use this measuring unit to indicate the strength of the magnets in our Magnetic Bracelets (Titanium Magnetic Bracelets, Stainless Steel Magnetic Bracelets, Gold Magnetic Bracelets, All-Magnets Bracelets, Golfers Magnetic Bracelets, Copper Magnetic Bracelets, Stone Magnetic Bracelets, Alloy Magnetic Bracelets, Expanding Bracelets and our Extra Large Bracelets), All our Magnetic Bangles Titanium Magnetic Bangles, Silver Magnetic Bangles, Stainless Steel bangles, Copper Magnetic Bangles and the Economy Magnetic Bangles), our other Magnetic Jewellery (Our Magnetic Rings & Earrings, Magnetic Necklaces and chains, Magnetic Hematite jewellery and our Watches with magnetic bracelets), our Magnetic Therapy products (The General Magnetic Well-Being products and the Magnetic Body Support), and our Magnetic Animal Care (Pets Magnetic Care).
1. Placing the item in an external magnetic field will result in the item retaining some of the magnetism on removal.
2. Placing the item in a solenoid with a direct current passing through it.
When magnetizing objects, the results will be considered to be "soft" or "hard":
1. A "soft" or "impermanent" magnet is one that loses its memory of previous magnetizations. "Soft" magnetic materials are often used in electromagnets to enhance (often hundreds or thousands of times) the magnetic field of a wire that carries an electrical current and is wrapped around the magnet; the field of the "soft" magnet increases with the current.
2. A "hard" or "permanent" magnet is one that stays magnetized for a long time, such as magnets often used in refrigerator doors and magnetic jewellery. Permanent magnets occur naturally in some rocks, particularly lodestone, but are now more commonly manufactured.
A magnet's magnetism decreases when it is heated and increases when it is cooled.
Types of Magnets and Materials
1. Ferrite Magnets:
Permanent ferrite magnets (or "hard ferrites"), which have a high permanence after magnetization, are composed of iron and barium or strontium oxides. In a magnetically saturated state they conduct magnetic flux well and have a high magnetic permeability. This enables these so-called ceramic magnets to store stronger magnetic fields than iron itself.
Ferrites are produced by heating: an intimate mixture of powdered precursors are heated and pressed in a mould.
2. Alnico Magnets:
Alnico magnets are produced by casting or sintering processes. Anisotropic alnico magnets are oriented by heating above a critical temperature, and cooling in the presence of a magnetic field.
3. Neodymium-iron-boron (NdFeB) magnets:
4. Samarium-cobalt magnets:
5. Ceramic magnets:
Alnico magnets are produced by casting or sintering processes. Anisotropic alnico magnets are oriented by heating above a critical temperature, and cooling in the presence of a magnetic field
6. AlNiCo magnets:
7. Injection Molded/Bonded magnets:
8. Plastic magnets: