Hey guys, feels good to be writing again. This time I will be writing on magnets. I came across some magnets recently and I had fun playing with them, that was when I decided to write about them.
What is a magnet.
A magnet is any object that has a magnetic field. It attracts ferrous objects like pieces of iron, steel, nickel and cobalt. The Greeks in the early days, noticed that the naturally occurring magnet known as 'lodestone' attracted pieces of Iron. That started the journey into the discovery of magnets.
A horseshoe magnet
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These days magnets are formed artificially in numerous shapes and sizes depending on what it's to be used for. One of the most common magnets the bar magnet is a long, rectangular bar of uniform cross-section that attracts pieces of ferrous objects.
The end of a freely pivoted magnet will always point in the North-South direction. The end that points in the North is called the North Pole of the magnet and the end that points South is called the South Pole of the magnet. Scientists have proven experimentally that like magnetic poles repel each other whereas unlike poles attract each other.
Types of magnet
There are various types of magnet with different properties, some of them are explained below.
Permanent magnet.
These are type the of magnets that we know, they are very common and we come across them in our daily lives. Examples are the magnets on our refrigerators, the ones in our speakers. These magnets are said to be permanent, that is once they have been magnetized they retain a certain level/degree of magnetism. Permanent magnets are generally made of ferromagnetic materials. These materials are made up of atoms and molecules that each have a magnetic field and are placed to strengthen each other.
These permanent magnets are classified into four types and they are classified based on their composition.
- Neodymium Iron Boron (NIB)
- Samarium Cobalt (SmCo)
- AlNiCo
- Ceramic
The NIB and SmCo are the strongest types of magnets and they are extremely difficult to demagnetize. They are also referred to as rare earth magnets since their compounds come from the rare earth or Lathanoid series of elements that are found in the periodic table.
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AlNiCo is a compound made of ALuminium, NIckel and CObalt. Alnico magnets are commonly used magnets and first gained popularity in the 1940s. They are not as strong as NIB and SmCo and they can be easily demagnetized. Alnico magnet is least affected by temperature. This is also the reason why bar magnets and horseshoes have to be taken care of to prevent them from loosing their magnetic properties.
Ceramic magnets are the most popular today, they can also be referred to as ferrite. They were first developed in the 1960s.
Ceramic magnets are fairly strong magnets although their strengths varies with temperature changes. They can be in block, disc and ring form.
A ceramic magnet
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Permanent Magnets can be further classified into Injection Moulded and Flexible magnets. Injection molded magnets are a composite of various types of resin(Any of various yellowish viscous liquids or soft solids of plant origin; used in lacquers, varnishes and many other Applications; chemically they are mostly Hydrocarbons, often polycyclic) and magnetic powders, permitting parts of complex shapes to be manufactured by injection molding. The physical and magnetic properties of the product depend on the raw materials, but are generally lower in magnetic strength and resemble plastics in their physical properties. Flexible magnets are similar to injection molded magnets, using a flexible resin or binder such as vinyl, and produced in flat strips or sheets. These magnets are lower in magnetic strength but can be very flexible, depending on the binder used.
Demagnetization: This is the process of getting rid of the magnetic field in an object.
Permanent magnets are demagnetized by:
Heat - Heating a magnet until it is red hot makes it loose its magnetic properties.
Contact with another magnet - stroking one magnet with another in a random fashion, will demagnetize the magnet being stroked.
Hammering or jarring will loosen the magnet's atoms from their magnetic attraction.
Temporary magnets
Temporary magnets are those magnets that act like permanent magnets when they are within a strong magnetic field. However, they loose their magnetism when the field disappears. Paperclips, iron nails and other similar items are examples of temporary magnets. Temporary magnets are used in telephones and electric motors amongst other numerous things.
Electromagnets
Electromagnets are very important to man because without them things that are now very useful won't be things such as computers, televisions and telephones. Electromagnets are very strong magnets, they are produced by placing a metal core (usually an iron alloy) inside a coil of wire that carries an electric current. The electricity in the current produces a magnetic field.
NOTE:The strength of the magnet is directly proportional to the strength of the current and the number of coils of wire. Its polarity depends on the direction of flow of current. While the current flows, the core behaves like a magnet. However, as soon as the current stops, the core is demagnetized.
Superconductors
superconductors are the strongest magnets. They don't need a metal core at all, but are made of coils of wire made from special metal alloys which become superconductors when cooled to very low temperatures.
Uses of magnets
Magnets are used for various things and especially in industries around d world.
USES OF MAGNETS IN INDUSTRIES
Separation
Different kinds of magnetic carriers, plates, separators, pulleys and grates are used to separate impure material containing iron from high volume industrial flow. Like magnets are also used to recover objects containing from the depths of the sea.
Magnetic sweepers
Magnetic sweepers are used in industries to help reduce maintenance costs and eliminate flat tires at airports, loading docks and work stations.
Sorters
Magnets can also be used for sorting magnetic material from non-magnetic material. Magnets are also used to separate Iron from Ore in the mining industry. Food manufacturing factories use magnets to prevent small iron particles from mixing with the food.
USES OF MAGNETS IN ELECTRONICS
Televisions
All Televisions have magnets inside of them that make them work. These cathode ray tubes have an electron gun in the neck of the tube that shoots a stream of electrons toward the screen. Normally these electrons travel in a straight line and strike the screen at a central spot.
But powerful electromagnets in the tube's neck deflect the electrons toward the top or bottom and left or right sides of the tube. The inside of the screen has a special coating that glows when the stream of electrons strikes it. In this way, magnets help us see images on the TV screen.
Video tapes
Video tapes use a similar material with iron compounds this material allows magnetic fields to be stored in the different patterns on the tape.
Storage disks
Computer storage disks are coated with an iron material that stores tiny magnetic fields in a pattern, and that is how data are stored on the computer disks. Just like television screens, computer screens also use magnets in a similar manner.
Other uses of magnets are:
Credit card / ID card: Magnets are also used to make the everyday credit cards and other types of ID that we use.
Around the house: In the house appliances such as Plug-in battery eliminators, TV deflection coil, TV degaussing coil, Computer monitor deflection coil, Computer hard drive recording and reading head, Dishwasher water valve solenoid, Shower curtain weights / attach to tub, Headphones, Stereo speakers, Computer speakers, Telephone receivers, Phone ringers, Microwave tubes, Doorbell ringer solenoid, Refrigerator magnets to hold things, Seal around refrigerator door, Power supply transformers and lots more! are all functional because of magnets.
Chemistry: Chemists use nuclear magnetic resonance to characterize synthesized compounds.
Toys: Given their ability to counteract the force of gravity at close range, magnets are often employed in children's toys, such as the Magnet space wheel and Levitron, to amusing effect.
MAGNETIC FIELD OF THE EARTH
Earth's magnetic field
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The magnetic field of the earth is like that of a bar magnet. So how did the Earth get its magnetic field?
Magnetic fields surround electric currents, so we presume that circulating electric currents in the red hot metallic core of the earth are the beginning of the magnetic field.
The Earth's magnetic field has been attributed to the circulating electric current (dynamo effect), but it does not have a constant in direction.
The Earth's rotation plays a part in generating the currents which are assumed to be the source of the magnetic field. The Mariner 2 (an American space probe to planet Venus) found out that Venus does not have such a magnetic field although its core iron content must be similar to that of the Earth. Venus's rotation period of 243 Earth days is just too slow to produce the dynamo effect.
It is now believed that the Earth's magnetism is due to the magnetic effect of current which is flowing in the liquid core at the center of the Earth. This makes the Earth a huge electromagnet.
Conclusions
Well guys, there you have it, I hope this article about magnets has enlightened you on how important magnets are to us. Magnets are used in almost every electronics that is produced. As life goes on the importance of magnets will grow massively as the world of technology can't do without it.
I have some ceramic ring magnets from spoilt speakers that I joke around with all the time.