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A CCD (charge-coupled device) has a grid of sensors that react to light.
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.

There are a lot of different types of sensors. Sensors are used in everyday objects.

Thermal sensors[change | edit source]

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[change | edit source]

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).

This is any thing that can be used to find things like photons, electrons, 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 will show up on the wall or will be picked up on the CCD and can be viewed on an attached TV screen or something like that. When an electron hits the screen it make a phosphor glow there.

Mechanical sensors[change | edit source]

  • Pressure sensors: barometer
  • Vibration and shock sensors

Motion sensors[change | edit source]

A motion sensor detects physical movement in a given area.

Car sensors[change | edit source]

  • reversing sensor
  • rain sensor