Written by Ojjas Bhandari; Edited by Laura Ionescu
Also published by Futuristic Photons and The Society of Physics
Superconductivity was discovered by Heike Kamerlingh Onnes in 1911.
Superconductors are of immense importance, as they can help us power grids, aid telecommunication, medical imaging, drug analysis, and more. The sole problem here appears to bs the low temperature at which superconductivity can occur. However, this has been overcome!
Basic criteria for a good superconductor is strong bonds and lightweight metals. Hydrogen has been already metalized under extreme pressure, and it forms the strong bonds due to the smallest atomic radii. This enabled superconductivity to occur at room temperature.
Scientists finally achieved superconductivity at 15 degrees Celsius , which will revolutionize the world. (they had previous broken the record of -23 degrees Celsius)
Superconductivity refers to the property that some materials have which enables them to carry current with no resistance (this does not mean that the electrons do not move at all, but that they possess really low kinetic energy, and they continue to move through a small number of collisions). Since they possess such low kinetic energy, the probability of collisions of electrons decreases drastically. There are already many alloys with really low resistance, but by reducing temperature even further we can also reduce resistance.
[Temperature is defined as the “Average Kinetic Energy per particle”.]
Below a limit called ‘critical temperature’, the resistance suddenly falls to zero . This is also explained by the Berdee-Cooper-Schrieffer Theory, which describes how the electron pairs flow through a material.
According to this theory, a pair of electrons are bounded (not bonded) at low temperature(s) in a specific manner (called Cooper Pairs), which condensed them, causing superconductivity to occur as a microscopic effect. A pair of electrons means that both the electrons share the same energy state, and in a cooper pair, the electrons are arranged in such a way that their “net angular p is equal to zero”. This is a case of violation of the Pauli Exclusion Principle.
Pauli Exclusion Principle states that two Fermions in the same Quantum System cannot possess the dame Quantum State. A Quantum System is an Isolated System, which is observed periodically.
However, electrons still vibrate, thanks to the Heisenberg Uncertainty Principle, due to which we can neither find the exact position nor the exact momentum of a particle. If electrons won’t move, it would mean that their momentum would be equal to zero, which contradicts the theory of *Mr. Heisenberg*.
∆x ∆p ≥ h/4π
Where, “∆x” is difference in initial and final positions of particle during observations and “∆p” is the difference in initial and final momentum of particle during observation. “h” is Planck’s constant and “π” is ratio of circumference to diameter.
Therefore p = 0 isn’t possible for particles, the same goes for their position. Confused?
Let ∆p = 0 or ∆x = 0, so now, on the left hand side, you have 0, and on right hand side you have h/4π, whose value is 5.272 x 10^-35 m² kg/s. (which is a positive real number)
Since the principle talks of particle wave nature, therefore the particle can neither have a definite momentum nor definite position.
Another aspect of superconductivity is the Meissner Effect.
This deals with a superconductor rejecting the magnetic field of a magnet brought closer to it, causing the Magnet to repel — forming the basis of MagLev trains. In fact, this effect has really wide applications in in day to day tasks.
This basically happens because when a superconductor is placed in a magnetic field F and moved, current starting to flow through the superconductor’s surface due to induction. The current induced produces another magnetic field whose direction is exactly the opposite to the magnetic field produced by the magnet, therefore causing repulsion of that magnet. Furthermore, since Super Conductors have no resistance and the current is directly proportional to the Magnetic Field produced, you can imagine the intensity of the magnetic field very well, and that is why it tends to reject the magnetic field.
Now you know the Meissner’s effect, the theory.
The superconductivity works in a really different manner. For example, superconductivity hasn’t been observed for Copper, Silver, and Gold.
Let’s consider for ohmic conductors.
V=I * R (I times R)
In ohm’s law, while solving superconductivity problems, the R is taken to be zero, but vibrations do exist.
V = I*0
V/O = I = (infinity)
So without changing the voltage, we are able to achieve Infinite Current,
Remember this doesn’t happen for normal materials at normal temperatures. It requires superconductors or any alloy to be present at its critical temperature.
This discovery of superconductivity at normal temperatures will help us and our future generations to use superconductors as a part of nature itself, without lowering temperatures and without more artificial supplements!
hARTS magazine 