# Superconductivity

Essay by Anonymous UserCollege, UndergraduateA, March 1997

INTRODUCTION

We've all heard about superconductivity. But, do we all know what it

is? How it works and what are its uses? To start talking about

superconductivity, we must try to understand the how 'normal' conductivity

works. This will make it much easier to understand how the 'super' part

functions. In the following paragraphs, I will explain how superconductivity

works, some of the current problems and some examples of its uses.

CONDUCTIVITY

Conductivity is the ability of a substance to carry electricity. Some

substances like copper, aluminium, silver and gold do it very well. They are

called conductors. Others conduct electricity partially and they are called

semi-conductors. The concept of electric transmission is very simple to

understand. The wire that conducts the electric current is made of atoms

which have equal numbers of protons and electrons making the atoms

electrically neutral. If this balance is disturbed by gain or loss of electrons,

the atoms will become electrically charged and are called ions.

Electrons

occupy energy states. Each level requires a certain amount of energy. For an

electron to move to a higher level, it will require the right amount of energy.

Electrons can move between different levels and between different materials

but to do that, they require the right amount of energy and an 'empty' slot in

the band they enter. The metallic conductors have a lot of these slots and

this is where the free electrons will head when voltage (energy) is applied. A

simpler way to look at this is to think of atoms aligned in a straight line (wire).

if we add an electron to the first atom of the line, that atom would have an

excess of electrons so it releases an other electron which will go to the

second atom and the process repeats again...