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Sensors and Detectors

by Ron Kurtus (revised 3 January 2014)

A sensor or a detector is a device that responds to a stimulus, such as heat, light, or pressure. It then generates a signal that can be measured or interpreted.

Humans, animals and even plants have sensors that can detect the world around them. Detectors are used in physical science to respond to energy signals and forces.

They are necessary for measurements and experiments. Signals can be manipulated to make their information more usable.

Questions you may have include:

This lesson will answer those questions. Useful tool: Units Conversion



Living sensors

Humans, animals and plants have sensors that detect signals from the world around them.

Humans and animals

Humans and animals can detect various forms of energy through their sensors or detectors:

Some animals can also detect electrical signals and magnetic fields.

(See Using Your Senses for more information on this subject.)

Plants

Plants have the ability to detect or sense various forms of energy. They detect light, heat, touch, certain chemicals, and gravity. Examples include:

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.

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.

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.

Amplifiers

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

Filtering

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.

Summary

A sensor or a detector is a device that responds to a stimulus or form of energy. It then generates a signal that can be measured or interpreted. Humans, animals and even plants have sensors that can detect the world around them. Detectors are used in physical science to respond to energy signals and forces. They are necessary for measurements and experiments. Signals can be manipulated to make their information more usable.


Observe the world around you


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