The transducer may be defined as any device that convert the energy from one form to another, Most of the transducers either convert electrical energy in to mechanical displacement and convert some non electrical physical quantities like temperature, Light, Pressure , Force , Sound etc to an electrical signals. In an electronics instrument system the function of transducers is of two types.
They required an external power supply and therefore output is equal to the variation in a physical parameter such as pressure, temp etc
The self generated transducers don’t use the external power supply source. However they provide an electrical output when stimulated by some physical form of energy. The self generated transducers are sub divided into many groups.