Infrared Radiation: Definition, Uses & Effects

Lesson Transcript
Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

This lesson will explain what infrared radiation is and discuss a number of practical uses and effects of infrared, including its connection to climate change and the way the atmosphere responds to infrared waves. A short quiz will follow.

What Is Infrared Radiation?

Infrared radiation is made up of electromagnetic waves of a particular wavelength just beyond what we can see on the red side of the spectrum. They were first discovered by William Herschel around 1800.

Other electromagnetic waves include radio, microwaves, visible light, ultraviolet, x-rays, and gamma rays, but electromagnetic waves that are between 700 nm and 1 mm are classed as infrared. 1 millimeter is equal to 1,000,000 nanometers!

Infrared is all around us: Most warm objects, including the human body, release radiation of this wavelength, heat-sensitive cameras work by detecting infrared radiation, and half of the energy emitted by the sun is infrared.

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  • 0:01 What Is Infrared Radiation?
  • 0:47 Uses of Infrared Technology
  • 3:03 Effect on Climate Change
  • 3:32 Lesson Summary
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Uses of Infrared Technology Radiation

One of the most common uses of infrared radiation is in heat-sensitive thermal imaging cameras. These can be used to study human and animal body heat patterns, but more often, they are used as night-vision cameras. These have uses in warfare, as security cameras and in nocturnal animal research.

Infrared Image of a Human

Most remote controls operate by sending pulses of infrared, spelling out codes that an electronic device will recognize. This includes TV remotes, DVD players, projectors, etc. Infrared is often used to send signals through fiber optic cables, particularly when using standard silica fibers. Fiber optic cables are commonly used to transmit audio to sound systems and for high-speed Internet connections.

Infrared is also widely used in astronomy. Taking pictures of the universe in infrared can lead to some amazing discoveries. Astronomers can look at an area of the sky that appears empty and dark in the visual part of the electromagnetic spectrum and find the area full of activity in the infrared. Since most objects that are at all hot produce infrared radiation, whereas plenty of objects do not produce visible light, it is a vital tool in observational astronomy.

Image From Infrared Astronomy

One issue with infrared astronomy is that infrared tends to be absorbed by water vapor in the atmosphere. Positioning telescopes at high altitudes can help reduce this issue, as can putting telescopes in balloons or planes. However, since the Hubble Space Telescope was launched in 1990, we have entered a new era in infrared astronomy - space telescopes are able to conduct infrared photography with no interference from the Earth's atmosphere whatsoever. As a result, we have some stunning images that we could never have achieved on Earth.

We have detected many objects using infrared astronomy. These include cold and dark dust clouds heated by nearby stars, protostars that haven't begun to emit light, and planets that would be drowned out by their stars when viewed in visible light.

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