Question

At absolute zero temperatures ..... Materials become superconductive..... Electricity pass through them without any resistance ..... According to 'V=IR' , R becomes zero ,then if resistance becomes zero do u think that any kind of potential difference exists???? And if not ...how can electrons travel through a conductor??? at such weird temperatures?

Answer 1

The resistance of a regular metal at 0K is due to lattice imperfections. The more perfect you can get the metal, the lower the resistance at 0K.

There are a few metals that become superconductors near 0K, Lead and Mercury being two of them. Superconductivity is a very different phenomenon, though, and the subject of another discussion.

Zero Kelvin does not mean zero energy. The Pauli Exclusion Principle sees to that -- no two Fermions (electrons in this case) can occupy the same state with the same spin, so there are many moving electrons even at 0K, but none of them with energy above the Fermi level (the energy corresponding to the highest state occupied by an electron if there are no lower energy vacancies).


Higher temperatures don't actually mean higher energy, they actually mean higher probability that an electron will randomly jump into a higher energy level. At 0K none of them do.

so
we can understand that these laws are valid to normal conductors
so it is not true that here v=I
it is a special case
and those laws and equations are not aplicable at those conditions