Q.Define electrical noise.

Electrical noise is any unwanted electrical energy that tends to interfere with the easy and correct reception and reproduction of a wanted signal. In every communication system, besides the useful signal there is always some random, unwanted energy riding along with it, and this noise sets the limit on the smallest signal a receiver can usefully handle.

Noise has a few defining features that are worth remembering:

• It is random in nature, so it cannot be predicted exactly.
• It may be internal — generated inside the system by its own components — or external, arriving from outside sources.
• It can be minimised but never completely eliminated, so good system design aims to keep it as low as possible rather than remove it. …