2. An introduction to electric circuits

2.1. Electrical/electronic system block diagrams

   An electrical/electronic system is a group of components connected together to perform a desired function.
Figure2.1 shows a simple public address system, where a microphone is used to collect acoustic energy in the form of sound pressure waves and converts this
to electrical energy in the form of small voltages
and currents; the signal from the microphone is then
amplified by means of an electronic circuit containing
transistors/integrated circuits before itis applied to the
loudspeaker