Found Throughout Everyday Life
Common transducers that detect or transmit information include microphones, Geiger meters, pressure sensors, thermometers and antennae. A microphone, for example, converts sound waves that strike its diaphragm into an analogous electrical signal that can be transmitted over wires. A pressure sensor turns the physical force being exerted on the sensing apparatus into an analog reading that can be easily represented. Many people think of a transducer as being some sort of technical device, but they can be found in many places throughout everyday life.
Most transducers have an inverse that allows for the energy to be returned to its original form. Audio cassettes, for example, are created by using a transducer to turn the electrical signal from the microphone pick-up — which went through a transducer to convert the sound waves into an electrical signal — into magnetic fluctuations on the tape head. These magnetic fluctuations are then read and converted by another transducer — in this case, the stereo system — to be turned back into an electrical signal. This signal is then fed by wire to speakers that act as yet another transducer to turn the electrical signal back into audio waves.
Other transducers turn one type of energy into another form, not to measure something in the external environment or to communicate information, but rather to make use of that energy in a more productive manner. A light bulb, for example, converts electrical energy into visible light. Electric motors are another common form of electromechanical transducer, converting electrical energy into kinetic energy to perform a mechanical task. The inverse of an electric motor — a generator — also is a transducer, turning kinetic energy into electrical energy that can then be used by other devices.
Efficiency
As in all energy conversions, some energy is lost when transducers operate. The efficiency of a transducer is found by comparing the total energy put into it to the total energy coming out of the system. Some transducers are very efficient, and others are extraordinarily inefficient.
A radio antenna is one example of an efficient transducer. The antenna acts as a transducer to turn radio frequency power into an electromagnetic field. When the antenna is operating well, this process can be more than 80 percent efficient. Most electrical motors, by contrast, are less than 50 percent efficient. A common light bulb, because of the amount of energy that is lost as heat, is less than 10 percent efficient.
