Superconductivity 

Juan G Perez Narvaez

Not so much ago I saw a video of quantum levitation. The video was very interesting and I wanted to know how that was possible. When I looked this was possible by a phenomenon known as superconductivity. Superconductivity is a quantum mechanical phenomenon in which there is exactly zero electrical resistance. This was discovered by Heike Kamerlingh Onnes. 

What happens is that when a superconductor is cooled below its critical temperature is resistance drops to zero. This means that if we put an electric current in a loop of superconductive wire in a temperature lower than its critical temperature the current will continue flowing indefinitely with no power source. For normal conductor even when the temperature is near absolute zero there exists some resistance in them. In superconductor there is none at all. But the part that I want understand is why do the material levitate and stay locked in an specific point in space. And for that we look at one of the things that characterize superconductivity, and that is the Meissner effect.

The Meissner effect is the expulsion of a magnetic field from a superconductor during its transition to the superconducting state. In a superconductor above its critical temperature the magnetic field goes completely through them, but in a superconductor below its critical temperature the magnetic field does not go through it. It surrounds it and locks it in space.

  

In the pictures above we can see how the magnetic field distributes when the superconductor is above or below its critical temperature. We see that the field won’t let the superconductor move from where it is, unless we apply a force greater than the one generated by the field.

But what would be some uses for this discovery? In the field of levitation the superconductors are very useful. For example in transportation like trains extremely powerful conductors may be used to make train practically float and therefore eliminate friction between the wheels and the track. In medicine they use superconductors in MRI (Magnetic Resonance Imaging) for example. In Korea they have developed the Superconducting QUantum Interference Device that is capable of sensing a change in a magneticfield overa a million time weaker than in a needle in a compass. That is as little as e-14T. This means that people would not have to be exposed to strong magnetic fields.   Also superconductor a can be used in generators instead of using copper wire and other materials. This way the efficiency of the generator would be 99% more than the generator of copper wire, etc. In the military one of the uses of superconductor are in the deployment of “E-Bombs”. These bombs use superconductor to create a high intensity electromagnetic pulse to destroy enemy electrical equipment. These is better known as an EMP.

There are a lot of other uses for superconductors and with time there will be development of the uses of a superconductor. At first I only knew that the superconductor only where user to levitate, but know I know that there are a lot of uses for this phenomenon. And the uses help a lot the entire humanity.