A transducer is an electronic device that converts energy from one form to another (for example, converting light, sound, or mechanical pressure into electrical signals).

In energy transfers, there is always a Energy Input, a Process and a Energy output.

• For example a car engine: You put chemical energy into the tank which is the Energy input, the car engine itself is the process and the kinetic energy in the wheels and the engine is the Energy output. 

Energy transfers never transfer one type of energy into another by 100%.There is always a portion that is transfered into other types of energy.

• For example the car engine: A portion of the chemical energy is transfered into heat or thermal energy and into sound energy.

There are four main types of transducers:

• Ultrasonic transducer

• Temperature transducer

• Pressure transducer

• Piezoelectric transducer