Electronics and Communication
The field of electronics comprises the study and use of systems that operate by controlling the flow of electrons (or other charge carriers) in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is an integral technique in the field of electronics engineering and is equally important in hardware design for computer engineering. All applications of electronics involve the transmission of either information or power. Most deal only with information.
A semiconductor behaves as an insulator at very low temperatures, and has an appreciable electrical conductivity at room temperature although much lower conductivity than a conductor. Commonly used semiconducting materials are silicon, germanium, gallium arsenide, indium phosphide, and mercury cadmium telluride.
A semiconductor can be distinguished from a conductor by the fact that, at absolute zero, the uppermost filled electron energy band is completely filled in a semiconductor, but only partially filled in a conductor.
The distinction between a semiconductor and an insulator is slightly more arbitrary. A semiconductor has a band gap which is small enough such that its conduction band is appreciably thermally populated with electrons at room temperature, whilst an insulator has a band gap which is too wide for there to be appreciable thermal electrons in its conduction band at room temperature.
An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, and switches.
An electrical circuit is a network that has a closed loop, giving a return path for the current. A network is a connection of two or more components, and may not necessarily be a circuit.