WHAT IS SUPERCONDUCTIVITY?
Superconductivity is the phenomenon by virtue of which a material obtains zero resistance. In a superconducting state, electrical resistance of a material vanishes and magnetic fields are, not absorbed, but expelled by the conductor.
WHAT’S RESISTANCE?
Resistance is the characteristic property of substances to “resist” the flow of electrons through them.
THE flow of electrons is what causes for electric charges to move, creating a form of energy which is referred to as “Electricity”.
Since Unlike charges attract and like charges repel each other, when electrons are moving through a current carrying conductor, the more positively charged the conductor is, the higher is the resistance offered.
Therefore, this is also why metals are good conductors of electricity, since they tend to lose electrons and acquire a positive charge to attain the stable state. Hence, they attract electrons and make them move slower.
Meanwhile, insulators like plastic offer very less obstruction to electric current. Therefore, they repel electrons and make them move faster
A superconductor offers zero resistance to the electron flow through them.
WHY IS THERE ZERO RESISTANCE? (HOW IS IT EVEN POSSIBLE?)
For explaining this phenomenon, consider an isolated electron going through a positively charged conductor. Let there be very low temperatures so that the vibrations are negligible and thermal effects are ignored.
Now, the atoms around which the electron is flowing have lost their electron due to the electric current flowing through them (current knocked off their electron). Therefore, they are positively charged.
Now, since unlike charges attract each other, the electron and the positively charged atom will attract each other.
If you now consider many positively charged atoms attracted to the single electron, the disturbance created in the conductor will be a bit more “positively charged” than the isolated positively charged particles.
Therefore, this disturbance should attract the other electron.
However, like charges repel
Therefore, the two electrons won’t completely unite but they would bind with another, resulting in the formation of what is known as a “Cooper pair”. (because there are many more positively charged particles attracting the electrons, the electron simply neglects electron-electron repulsion and goes with the initial electron through the conductor)
Then, different cooper pairs overlap, forming a network, which is unlikely to ever collide with the positively charged particles because the electrons are now attracted to each other. This network, though, still flows through the conductor
The reason as to why the network still flows is not yet explained fully. These are the results of the BCS Model for Superconductivity.
HOW CAN SUPERCONDUCTIVITY HELP US? (for next time…………)
+ I will explain the reason further in the next post
