Device in which a varying input signal controls a flow of Energy to produce an output signal that varies in the same way but has a larger
amplitude; the input signal may be a Current, a Voltage, a mechanical Motion, or any other signal, and the output signal is usually of the same nature.
The ratio of the output voltage to the input voltage is called the voltage gain.
The most common types of amplifiers are electronic and have Transistors as their principal components. In most cases today, transistors are
incorporated into Integrated Circuit chips. Most amplifiers include more than one transistor. Transistor
amplifiers are used in Radio and Television transmitters and receivers, stereophonic record players, and intercoms.