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Permanent Magnets – The Most Popular Magnet Choice

There are three main types of magnets, permanent magnets, temporary magnets and electromagnets.  Of these three types, permanent magnets are the ones the average person is most familiar with.  A good example of a common, everyday permanent magnet is a fridge magnet.

 

Permanent magnets are considered permanent because once they are magnetized they keep their level of magnetism. A permanent magnet is an object made from a material that is magnetized and it creates its own persistent magnetic field.

 

Permanent magnets can be created in almost every possible shape.  A good permanent magnet should produce a high magnetic field with a low mass.  In addition, when you are looking for qualities of a good permanent magnet you want to ensure the magnet is stable against the influences that can demagnetize it.

 

There are a number of different types of permanent magnets and each type has different characteristics and properties.  What differentiates these permanent magnets includes:

• How easily they can be demagnetized
• How strong they are
• How their strength changes depending on the temperature

 

Types of permanent magnets include:

• Neodymium
• Samarium-cobalt
• Alnico
• Ceramic (also known as ferrite)

 

Neodymium and samarium-cobalt magnets are classified as rare earth magnets.  Rare earth magnets are permanent magnets that produce the largest magnetic flux with the smallest mass. These magnets are known for being the strongest of all the permanent magnets and are difficult to demagnetize.

 

Alnico's name is derived from its components.  Alnico is made of aluminum, nickel and cobalt.  This type of permanent magnet is not easily affected by temperature, however it is easily demagnetized.

 

Finally, ceramic or ferrite magnets are perhaps the most popular type of magnet, mostly because of their flexibility. Ceramic magnets are flexible and often thin, meaning that they can be bent and moved in a number of different ways, making them excellent choices for advertising and marketing purposes. Ceramic magnets are fairly strong and not easily demagnetized, however their strength varies greatly according to the temperature.

 

The uses of permanent magnets vary greatly, including:

1. Mechanical applications rely on the attractive and repelling force of the magnet. Such applications include:

• Magnetic separators, magnetic holding devices
• Magnetic torque drives
• Magnetic bearing devices

1. Electrical energy applications rely on using the magnetic field of a magnet to convert mechanical energy into electric energy. Such applications include:

• Generators and alternators
• Eddy current brakes

1. Mechanical energy applications rely on using the magnetic field of a magnet to convert electrical energy to mechanical energy. Such applications include:

• Meters
• Motors
• Speakers
• Relays

1. Applications that are meant to direct, shape and control electron and ion beams do so using a magnet's magnetic field.  Such applications include:

• Ion Pumps
• Cyclotrons
• Cathode-ray tubes

 

Permanent magnets are the most commonly known magnet and are used in a variety of products and environments.  When choosing a permanent magnet you want to consider its strength, performance in temperature and whether it is easily demagnetized.

About the Author

Open since 1984, Jobmaster Magnets is the only designer, manufacturer and customized magnet supplier in Canada. Contact Jobmaster Magnets at 1-866-526-7164 or visit www.jobmastermagnets.com to enquire about customizing permanent magnets for your business or home.

If you hold a small magnet to an iron paperclip, the paperclip becomes magnetized for a short period of time,?

and then goes back to being non-magnetic, why?

It might help to think of magnetism by conceptual modeling.

I assume that you have played with a permanent magnet around a magnetic compass and observed its behavior before. As you can see, bringing the permanent magnet near the compass causes the compass to deflect in the direction of the permanent magnet.

Now pretend that inside a non-magnetized piece of iron, say your paper clip, that there are hundreds of tiny, randomly-oriented compasses that are free to spin. When you bring a permanent magnet near, all of the tiny compasses spin to align themselves with the magnet, and the result of this is that the paperclip is attracted on the whole to the magnet.

However, while these little compasses are free to spin, they also have a tendency to go back to their original random orientation. When you remove the permanent magnet, they go back to where they were at first.

It is interesting to note that if you leave a paperclip in a magnetic field for a long time, those tiny compasses fundamentally change and align themselves from their random orientation into something organized and oriented towards the permanent magnet. As a result, such a paperclip will become a permanent (although weak) magnet in and of itself.

Magnet - Hold On (Lindstrom Original Mix)