Types Of Magnets

Magnets are objects which have a magnetic field around them which attracts or repels certain materials. Magnets are recognized by many for their property of attracting metals. Magnets have tremendous applications in our daily lives and in various industries.

They are used in toys, appliances and hundreds of house hold things and are mostly used in industries such as: mining and mineral industry, ceramic powder industry, plastic and glass industry and many others.

Magnets come in different shapes, sizes and strength. They can be either man made or may exist in nature. So broadly we can say that there are two major types of magnets:

• Man made magnets
• Natural magnets

The natural magnets are called magnetite. They are rich in iron and minerals.

The man made synthetic magnets which are stronger than naturally occurring magnets are made of metallic alloys and some other methods.

The man made magnets are used for thousands of purposes and vary in their resistance and magnetic properties.

Following are three types of man made magnets:

• Permanent magnets
• Temporary magnets
• Electromagnets

The permanent magnets are very strong and are the most commonly used magnets.

These magnets are so called because once they get magnetized they retain their magnetism.

The reason for this is that these magnets are made of substances which contain atoms and molecules having magnetic fields which reinforce each other.

However under certain provided conditions these magnets may lose their magnetism, for example in shock.

The more resistant the magnet will be towards demagnetism the stronger it will be.

Permanent magnets have vast uses, from the stick-ons of refrigerator to many large industries, their magnetism is used. They come in various sizes and shapes and vary in their composition.

Some common types of permanent magnets are:

• Ceramic
• Alnico magnets
• Samarium cobalt
• Neodymium iron boron
• Flexible magnets

Of the above samarium cobalt magnets and Neodymium magnets belong to the category of rare earth magnets.

• Ceramic
  
  Ceramic magnets are also called ferrites and are composed of iron oxide and barium or strontium carbonate. These are really strong magnets and are largely used in scientific laboratories. They are the most commonly used magnets for experimental purposes.

• Alnico
  
  The alnico magnets are very strong magnets which are used as a replacement for ceramic magnets for various experiments because they are more stable and are more resistant towards demagnetization. However they are not as common because they are more expensive.

• Samarium Cobalt
  
  Samarium cobalt magnets belong to the category of rare earth magnets. These magnets have a very high magnetic strength and are very resistant towards demagnetization and oxidation. Samarium cobalt magnets are very expensive and are used in for applications which require high magnetism and high resistance. They were first introduced in 1970s.
• Neodymium Iron Boron
  
  These are another type of rare earth magnets. They are quite similar to samarium cobalt magnets but are less resistant. They are extremely strong magnets. An inch of this magnet is capable of lifting a metallic substance of several pounds. Because of their extremely high magnetism they are the most expensive magnets of the world and due to their high cost they are less used.

• Flexible
  
  The flexible magnets are produced in flat strips and sheets. These magnets have least magnetism.

Temporary Magnets

The temporary magnets are those magnets which act as magnets only when placed in a strong magnetic field provided by a strong magnet. Any metallic objects such as paper clips and nails when placed in a strong magnetic field can act as magnets.

However once removed from the field, they instantly lose their magnetism. Temporary magnets despite of their temporary magnetism have many useful applications. Mostly they are used in telephones and electric motors.

Electromagnets are very strong magnets which are different from the above mentioned magnets. These magnets work on the principle that a wire containing electric current produces a magnetic field.

It consists of a heavy metal core which is wounded by a wire coil. When current is passed through the wire it produces a magnetic field which in turns magnetizes the metal core.

The polarity of the magnet can be changed by controlling the amount of the current flowing and by changing its direction. They are commonly used in televisions, radios, video tapes, computers, speakers etc.