MATERIALS AND TYPES

MATERIALS:

                All the physical things are known as material.

There are three type of material regarding heat and current transfer.

         1.       Insulator

         2.       Conductor

         3.       Semi-conductor

INSULATOR:

  The material which does not allow follows the heat or current through it is called insulator. Such as wood, plastic and rubber etc.

band gap

 A band gap is the distance between the valence band of electrons and the conduction band. Essentially, the band gap represents the minimum energy that is required to excite an electron up to a state in the conduction band where it can participate in conduction.. In insulator material there is great band gap between conduction band and valance band

 CONDUCTOR:

  The material which allow to follows electricity or current through it is called conductor. Such as wire, water etc.

band gap

 In conductor material there is nearly no band gap.

SEMI-CONDUCTOR:

  Semiconductor is those material which neither a good insulator nor a good conductor in formal condition it acts as insulator bur if we change its properties it become conductor. Such as silicon and germanium.  

band gap

In semi-conductor material the band gap is higher than conductor and less than insulator due to this property it have dual characteristic of conductor and insulator.

SILICON:

  Silicon is the best semi-conductor at all it have 14 atomic number and 28 mass number which as shown in figure as. 

silicon

GERMANIUM:

  Germanium is also a semi-conductor and having of 32 atomic numbers and 64 mass number as shown in figure given below. It is thermally unstable.

germanium

 According Bohr atomic theory there are three type of element found in atom

      1.       Proton

      2.       Electron

      3.       Neutron

 In this sequence proton have positive charge, electron have negative and neutron is neutral have and have no charge on it.

Points to note:

   Ø  Insulator have tightly bounded electron so it difficult to move electron from valence shell.

   Ø  In conductor the valance electron are loosely bounded.

   Ø  In semi-conductor the electron are tightly bounded as conductor bur loosely bounded as insulator.

   Ø  Energy levels increase by increasing distance between atom to  nuclease to the shell.so electron 

           farthest from atom have high energy levels, while the nearest to atom have less energy levels.