Electrical Noise

any unwanted form of energy tending to interfere with the proper and easy reception and reproduction of wanted signals.

Classification

Based on Origin

1. External noise

             a) Atmospheric

             b) Extra-terrestrial

                                 i. solar

                                 ii. Cosmic

            c) Industrial

2. Internal noise

          a) Thermal Agitation Noise 

          b) Shot Noise

          c) Transit Time Noise

          d) Flicker Noise

           e) Miscellaneous Sources

Thermal noise

Thermal Agitation Noise

Also known as Johnson noise or White noise .

Shot Noise