Answer: Input Transducers convert a quantity to an electrical signal (voltage) or to resistance (which can be converted to voltage). Input transducers are also called sensors. Examples: LDR converts brightness (of light) to resistance.

The output transducer transfers signal out of the electrical domain and into the domain that can be perceived by one of the five human senses. A substantial amount of power is usually required to transfer information out of the electrical domain. An output transducer can: Produce sound with a speaker or buzzer.