physics - college

Superconductivity

The phenomenon of sudden disappearance of electrical resistivity of a material at a particular temperature is called superconductivity

Critical temperature

The temperature at which the resistance of a material becomes zero

Critical field

The minimum magnetic field required to destroy the superconductivity of a material below it's critical temperature

Formula of Hc

Hc (T) = H(0) [ 1 - ( T/Tc)²]

Meissner effect

The phenomenon in which a superconductor expells out magnetic flux lines from it's interior when cooled below it's critical temperature

Proof of Meissner effect

B = u₀(H + M)

B = u₀( H + XH)

B = u₀H ( 1 + X)

We know for a superconductor B = 0

0 = u₀H(1 + X)

Case-1 Case-2

u₀H = 0 1 + X = 0

=> X = -1

Difference btwn type 1 and type 2 superconductor

Define bcs theory

It is a microscopic theory that explains superconductivity based on the formation of bound electron pairs known as cooper pairs

Formulated by John bardeen, leon cooper and john robert schreiffer.