Sensor

300px|thumb|A television tube or other CRT (cathode ray tube) detects electrons on its screen.

A sensor is a device that measures a physical quantity and converts it into a 'signal' which can be read by an observer or by an instrument. For example, a mercury thermometer converts the measured temperature into the expansion and contraction of a liquid which can be read on a calibrated glass tube.  Video cameras and a digital cameras have an image sensor.

There are many different types of sensors. Some are used in everyday objects, and some are separate.

 Thermal sensors 
A sensor that detects temperature. Thermal sensors are in many laptops and computers in order to sound an alarm when a certain temperature has been exceeded.
 temperature sensors: thermometers, thermostats
 heat sensors: bolometer, calorimeter

 Electromagnetic sensors 
An electronic device used to measure a physical quantity such as pressure or loudness and convert it into an electronic signal of some kind (e.g. a voltage).
 electrical resistance sensors: ohmmeter
 electrical voltage sensors: voltmeter
 electrical power sensors: watt-hour meter
 magnetism sensors: magnetic compass
 metal detectors
 Radar

An electromagnetic sensor is anything that can detect things like photons, electrons, magnetic fields etc. It can be as simple as a white wall, a sheet of white paper, etc., or as new as a charge-coupled device. When a laser is aimed at a detection screen, a bright spot can be seen on the screen, or when an electron hits the phosphors on another kind of screen, it makes that screen glow.

 Mechanical sensors 
 Pressure sensors: barometer
 Vibration and shock sensors

 Motion sensors 
A motion sensor detects physical movement in a given area.
 Radar gun, tachometer
 Speedometer

 Car sensors 
 reversing sensor
 curb feeler


Category:Tools
Category:Computer hardware
Category:Data input