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Sensors & Detectors

Detectors in science

In order to study anything in science, you must first be able to detect it. The most interesting things, of course, are those that we can detect with our own senses. We then use devices to amplify what we can sense, in order to study those energy forms more thoroughly.
We also use detectors to study energy forms that we are not able to sense, such as magnetic fields. Detectors and sensors make up the starting point for most scientific studies.

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Man-made detectors

Scientists have invented various types of sensors to detect energy forms. For example, a smoke detector in you home will set off an alarm when the energy from smoke or heat reaches its detection device. The microphone on you tape recorder detects the energy from sound waves and creates an electric signal that records the sound.

  • Solar cells and photographic film detect light.
  • Microphones detect sound.
  • Thermometers sense the change in heat or temperature.
  • Pressure gauges detect touch.
  • Scales detect and measure the effect of gravity.
  • There are many devices that detect various chemicals and even odors.
  • A magnetometer detects magnetic fields.
  • An electric meter detects electricity.
  • A Geiger counter detects atomic radiation.

Changing signals

The signals received by a detector may often be manipulated to gather desired information. Often the signal received is weak, so it must be amplified. Sometimes the signal is too strong, so it must be filtered. Extraneous signals and noise also must sometimes be filtered out, so that only the desired signal comes through.


Besides detecting energy forms, many devices amplify or enlarge the signal. Some are mechanical, but most amplifiers are now electronic. Examples of amplifiers include:

  • A telescope makes distant objects appear closer.
  • Electronic amplifiers can increase the level of sound
  • Very faint chemical signals (odors or tastes) can be amplified electronically to give their details.


If you would try to study the Sun, the light would be too bright to view or photograph. A filter could be used to lower the light level. It could also filter out all colors except those that you want to measure.
Sometimes electrical signals on the radio or television include static and other forms of noise. Electronic filters eliminate the noise and allow you to get a good, clear signal.

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