CHARGE

The deficiency and excess of electrons on any material is known as charge. Og excess of electrons is present than material is negatively charged similarly. if deficiency of electrons is present than material is positively charged.
EXPLANATION:
Charge is measured in coulomb and coulomb is denoted by "C". But charge is denoted by"Q". similarly coulomb is defined as " it is the value of charge that one ampere current is transfer it to one side to another side in one second

BASIC ELECTRONICS

Semi Conductor Theory

According to this theory there are three types of materials with respect to its resistance.

Conductor

It is stated as follow
The materials is called conductor which has a resistance of (10)^-6ohm-cm It is a small valve of resistance

Copper, Gold, Silver and Iron are the some examples of conductor

Semi-Conductor

It is stated as follow
The materials is called semi-conductor which has a resistance of (10)^2 ohm-cm It is a medium valve of resistance.
Germanium, silicon and carbon are the some examples of semi-conductor

Insulator

It is stated as follow
The materials is called Insulator which has a resistance of (10)^6 ohm-cm It is a high valve of resistance

Paper, Glass, Rubber, Wood and Oil are the some examples of insulators

Shell or Orbit

It is the path in which the electrons are moved or circulate around the nucleus of the atom

Valance Shell

Last shell of an atom in which electrons are moved is known as valance shell.

Valance Electrons

The no. of electrons which are present in valance shell of the atom is known as valance electron

Energy bands

It is the group of the energy levels who are very closer but separate to each other.

Types of energy bands

There are three types of energy bands

1). Filled Band
2).Valance band
3).Conduction band
Explanation of these bands is following there

Filled Band

A band in which minimum no. of free electrons are present is called filled band. This band is situated above on the valance band. In this band the electrons have low energy.

Valance Band

A band in which a large no. of free electrons is present is called valance band. This band is situated above on the conduction band. In this band the electrons have high energy.

Conduction Band

A band in which a large no. of free electrons is present is called valance band. This band is full fill with free electrons. This band situated below the valance band. In this band the electrons have very high energy.

Diagram

There are two main types of semi-conductor materials

1). Intrinsic semiconductor
2). Extrinsic semiconductor
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