Power-transforming device that enables energy
in any form (electrical, acoustical,
mechanical) to flow from one transmission
system to another. The energy flowing to and
from a transducer may be of the same or of
different forms. For example, an electric
motor receives electrical energy and delivers
it to a mechanical system; a gramophone
pickup crystal receives mechanical energy
from the stylus and delivers it as electrical
energy; and a loudspeaker receives an
electrical input and delivers an acoustical
output.