What a wonderful disrespect! In such a magnetic field, a body can levitate. You can quite easily obtain such a magnetic field by using at least 4 magnets, usually cubic ones, seated in a certain position. The body that levitates must be made of a diamagnetic material. Diamagnetism is the property of a substance to form a magnetic field which opposes to other magnetic fields, applied from the outside. This happens because the exterior magnetic field disturbs the rotation of the electrons around the nucleus of each atom.
The electrons oppose, just like you do when someone tries to get on your nerves. Small, but many! Diamagnetic materials are as common as they get. Easily explained, here are some that magnets do not stick to: wood, water, plastic, copper, etc.
However, you can find sets with 4 or even more cubes and a pyrolytic graphite, ready for levitation, on the market. On a similar system, but at another level, higher magnetic fields can be produced.
Electromagnets and other devices are used for this. Such devices are among the most powerful sources of magnetic fields. Because water is diamagnetic, any body rich in water is suitable for such an experiment. Berry and A. Geim, published in European Journal of Physics in Yes, a living being! Relax, nothing harmful happened to the frog; it simply became slightly confused. One of the most spectacular applications of magnetic levitation is the train system that uses magnetic fields to go forward by levitation.
This way, eliminating the friction, spectacular performances are obtained. These trains already compete with aircrafts. Especially if you take into account other advantages like low noise, no pollution, greater safety, etc. Imagine a future where, at least, big cities will be linked by high speed underground trains. Some kind of shaft subway.
You can get anywhere in only a few hours! Very close to teleportation… Did it ever strike your mind that levitation has something to do with this? Do you remember the school experiment where you rubbed a balloon or a plastic ruler on your hair or clothes, and afterwards it attracted small pieces of paper? Fascinating for any child! I think you already have a clue: if you could adjust the electrostatic field and find optimal positioning, then the small pieces of paper or other objects might raise to the electrostatic field, but without touching it.
And we would obtain electrostatic levitation! He says it is impossible to find an equilibrium point. The object can float, but in a chaotic way, which is not quite levitation. The puzzle was solved by Dr. He conceived a feedback system, which tracks the position of the object. To give you a glimpse of what this means, when the object goes too high or too low, the system adjusts the electrostatic charge very quickly, in order to bring it back to its initial position.
The result is a type of equilibrium. This is evident in this short video documentary. In this case, we are talking about sophisticated technologies:. Imagine that you can blow air continuously, so that the obtained force will compensate gravity. This is quite simple. As usual, stability is the real issue. Many solutions were found, but the most interesting, by its simplicity and good precision, is a conical nozzle that can carry in levitation mm spheres.
Bigger balloons can float relatively stable, but not sufficient enough to levitate. The fact is that aerodynamic levitation exists.
And it also has practical applications in various fields, such as glass production. A special version is the one called gas film levitation. Only in this case, because the lifting is done by the vehicle engines, it is debatable if this can be called levitation. But if a similar system is outside the lifted body, the conditions are satisfied. Some gases, like xenon, have rather high density. If high pressure is exercised upon them, the density can rise so much that it will attain fluid properties, or even solid properties.
An object can float on such a gas like a boat on water. This is buoyancy levitation. August 6, Explore further. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission.
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Does this seem correct? Nov 10, Related Stories. Aug 18, Jun 29, Swarms of tiny dumb robots found to carry out sophisticated actions Jul 23, Jul 19, Jul 15, Recommended for you. First observation of an inhomogeneous electron charge distribution on an atom 13 hours ago. Other diamagnetic materials are commonplace and can also be levitated in a magnetic field if it is strong enough. Water droplets and even frogs have been levitated in this way at a magnetics laboratory in the Netherlands Physics World, April This can only be done using the strongest magnetic fields that technology has produced.
The levitated objects sit inside the vertical cylindrical core of a hollow solenoid. Ref: M. Berry, A. Geim, Eur. Phys 18 , A high temperature superconductor in magnetic suspension. Earnshaw's theorem does not apply to diamagnetics, since they behave like "anti-magnets": they align ANTI-parallel to magnetic lines while the magnets meant in the theorem always try to align in parallel, as iron does paramagnetics.
In diamagnetics, electrons adjust their trajectories to compensate the influence of the external magnetic field, and this results in an induced magnetic field that points in the opposite direction to the external magnetic field. Superconductors are diamagnetics with the macroscopic change in trajectories screening current at the surface. The frog is another example, but the electron orbits are changed in every molecule of its body. Refs: W. Brandt, Science, , , Jan Oscillating Fields: an oscillating magnetic field will induce an alternating current in a conductor and thus generate a levitating force.
A similar effect can be achieved with a suitably cut rotating disc. The oscillating field is a way of making a diamagnet of a conducting body. Due to a finite resistance, the induced changes in electron trajectories disappear after a short time, but you can create a permanent screening current at the surface by applying an oscillating field, and conducting bodies behave just like superconducting bodies.
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