Transducer, in electronics, a device that converts electric energy into some other form of energy, or vice versa. Transducers are used in sound systems, in video equipment and in many measuring devices. A transducer used in a measuring device produces an electric current proportional to the strength or intensity of the physical quantity—such as heat, light, or mechanical stress—to which the transducer is subjected. Piezoelectric crystals (crystals that produce an electric current when deformed) and photoelectric cells are transducers; so are loudspeakers, which produce sound from electric energy.
About two-thirds of all adults partake in this mind-altering substance, yet many do not consider it a drug. But if you've ever seen someone who's had too much to drink, you know that alcohol has profound effects on the mind and body.
Criminals always leave traces behind after a crime is committed. In fact, footprints, tire tracks and tool marks are often more prevalent than fingerprints at a crime scene. What can impression evidence tell an investigator?