Transducers

A transducer is a device, usually electrical, electronic, electro-mechanical, electromagnetic, photonic, or photovoltaic that converts one type of energy to another for various purposes including measurement or information transfer (for example, pressure sensors). In a broader sense (for example in the Viable System Model) a transducer is sometimes defined as any device that converts a signal from one form to another. A very common device is an audio speaker, which converts electrical voltage variations representing music or speech, to mechanical cone vibration. The speaker cone in turn vibrates air molecules creating acoustical energy