Classification of Material—

Conductor—

The material which conduct electric current fairly well are called conductor.

Insulator—

The material which do not conduct electric current are called insulator.

Semiconductor—

These are the materials whose resistivities lie in between those of conductor and insulator.

Carriers of Current—

The charged particles which by flowing in a definite direction set up an electric current are called current carriers.

1. In Solid                                         Electrons
2. In Semiconductor Solids                n type—electron

P type---holes

1. In Liquid                                         Ions
2. Gases                                            Ions and Electrons
3. Vacuum Types                             Free Electrons