, motion, temperature, etc.When detectors detect the physical signal for which they are designed, they generate an electrical signal. Demodulators of RF receivers for radio or television that produce audio or video signals, or that are used to trigger an alarm
orother action, have a similar function.
Detectors are found in all sorts of engineering applications.
They are used for detecting differences in brightness and pulses of light such as those used in infrared sensors or motion detectors. Others, like photodetectors, detect the light signals in optical fibers and still others detect the finger touch on multi-touch screens.