Ø The input quantity for most instrumentation systems is nonelectrical. In order to use electrical methods and techniques for measurement, the nonelectrical quantity is converted into a proportional electrical signal by a device called transducer.
Ø Another definition states that transducer is a device which when actuated by energy in one system, supplies energy in the same form or in another form to a second system.
Ø When transducer gives output in electrical form it is known as electrical transducer. Actually, electrical transducer consists of two parts which are very closely related to Each other.
Ø These two parts are sensing or detecting element and transduction element. The sensing or detecting element is commonly known as sensor.
Ø Definition states that sensor is a device that produces a measurable response to a Change in a physical condition.
Ø The transduction element transforms the output of the sensor to an electrical output, as shown in the Fig.