It is the branch of science which deals with the electron flow through a vacuum, gas or semiconductor.
Classification of substances on the basis of conduction of electricity.
Solid
We know that, each substance is composed of atoms. Substances are mainly classified into three categories namely solids, liquids and gases.
In each solid atoms are at a definite positions and the average distance between them is constant.
Depending upon the internal arrangement of atoms, solids are further divided into two groups.
1. Crystalline Solids
The solid in which the atoms are arranged in a regular order are called the crystalline solids. In other words, we can say that in a crystalline solid. there is periodicity and regularity of its component atoms in all the directions. For example sodium chloride( common salt), diamond, Sugar, silver etc are the crystalline solids.
Their atoms are arranged in a definite geometrical shape. They have a definite melting point.
They are anisotropic, i. e., their physical properties such as thermal Conductivity refractive index etc, are different in different directions.
They are the real solids.
2. Amorphous Solids
The Solids in which the atoms do not have a definite arrangement are called the amorphous solids. They are also called the glassy solids. For example glass, rubber, plastic, power, etc are the amorphous solids.
Tbey do not have a definite arrangement of its atoms, i e., they do not have a characteristic geometrical shape.
They do not have a definite melting point.
They are isotropic. i. e., their physical properties such as conductivity of heat refractive index etc, are same in all the directions.
They are not the real solids.