Magnetic Levitation is a way to suspend objects in air without any support, as if in defiance of gravity. An unsung phenomenon of the past which is now being put to use in a variety of interesting and useful applications.
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As a child you must have seen a ping pong ball being levitated on an air stream at the output pipe of a vacuum cleaner. Magnetic levitation, also known as maglev is used in a similar way to levitate objects in air without any support, using magnetic field.
All magnets, whether natural or electromagnets, have two poles. We all known that like poles repel and unlike poles attract. Magnetic levitation is the product of the repulsion generated as a result of two magnetic fields. An object is said to be levitated when the force created by electromagnetic repulsion equalizes the weight of the object. Technically, it's the electromagnetic force counteracting the gravitational force.
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How Is Maglev Obtained?
It is proved that magnetic levitation cannot be obtained just by using static ferromagnetism, as the object would tend to gain instability. In order to create proper magnetic levitation condition, diamagnetic materials or superconductors have to be used. But in all these cases a little help from pseudo-levitation needs to be taken. Pseudo-levitation is a system that provides stability to the levitated object using a magnetic mechanism. For light objects, magnets made of diamagnetic materials are sufficient.
The atoms of a diamagnetic substance such as silver and bismuth, doesn't have a specific dipole moment. When these objects are brought under the influence of a magnetic field, a dipole moment is induced in the direction opposite to that of the field applied. Because of this a repulsive force is generated that creates the desired levitation.
Another way of obtaining magnetic levitation is by using electromagnetism. Electrodynamic fields are created when electricity is passed through a conductor. The moving charges that are created as a result of the magnetism, provides a vertical push that is equal to the gravitational pull, which in turn help to produce a stable levitation condition. Heavier objects are generally levitated by this method.
Apart from these main methods, eddy currents or electrodynamic suspension, oscillating magnetic fields and permanent magnet suspension are also used.
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Present And Future Use
Maglev train is a famous application of the maglev technology . Almost all the prominent countries have these trains as a major mode of transport in their system. Apart from this, maglev toys are also quite famous and are available in all the markets. Some of the famous maglev toys are maglev toy train, maglev toy cars, maglev clocks etc.
Future might see maglev technology put to use in a variety of applications. Maglev cars are supposed to be under development. These cars wont require a track but would fly in air. NASA is working on a maglev catapult that is predicted to reduce the costs and launching problems of a spacecraft. Also, Maglev elevators are already made and soon be put to use in Japan and China.