Infrared Radiation

Infrared radiation is an integral part of the electromagnetic spectrum. Even the light rays that we see are also a part of the same spectrum. Rays like gamma rays, alpha rays, X rays, etc. are also a part of the spectrum. 


In this case, students should note that every radiation in the spectrum has its wavelength. The division is based on this difference in wavelength. Infrared emissions, radio waves, microwaves, etc. have longer wavelengths whereas alpha rays, gamma rays, beta rays have shorter wavelengths. 


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Look at the picture above. It shows various types of rays and their position. The triangle presented right below the spectrum shows the visible spectrum that we see.

The former is likely to be less dangerous and harmful than the latter. However, the concern here is what is infrared radiation? So, students have to understand its background first as explained above, before going deeper into this specific type of radiation. 


What are Infra-Red Radiations?

The infrared radiation wavelength ranges between 700 nanometers and one millimeter. They have a longer wavelength than visible light and have a frequency of about 300 to 400 GHz.


The infrared radiation definition is crucial in understanding related concepts and its applications as well. Hence, students should note here that infrared radiations are not visible to the naked eye. Instead, they can only be felt by a human in the form of heat. 

Although infrared rays have specific properties similar to that of light rays, they are not the same. Features like polarising, reflection, etc. can be observed with infrared radiations.


What are the Uses of Infrared Radiations?

Before delving into the infrared radiation uses, students should be clear about a vital aspect. Infrared radiations are put into applications in two forms - rays and waves. The sources of infrared radiation and visible light are the heat or thermal rays. 

In broad terms, it is the sun and fire that are the prime sources of infrared radiations. 


However, they are trapped and used in multiple areas, including medical applications.

  • It is used as a source of heat based on the underlying infrared radiation meaning in areas like -

  • Treatment of high blood pressure

  • Chronic heart problems

  • Manufacturing factories

  • The other applications include infrared radiation uses in physical therapy. It warms the body and helps in muscle relaxation. 

  • The rays are also used in photography. Usually, digital cameras use this technique to click images. 


Out of all these applications, the infrared radiation therapy in both muscle relaxations and medical areas have gained immense significance. It is also hoped that the recent advancements will lead to further areas of applications.  


So, after reading the above lesson, students should also be able to answer the following questions. Give it a try for yourself and assess your knowledge.


Test Your Learning So Far

Fill in the blanks

  1. Infrared radiations have a wavelength higher than ……...…. nm.

  2. The visible spectrum has a wavelength ……....… than infrared radiation.

  3. X-rays have a wavelength ………….. than infrared radiation.

  4. ………... radiations are also called thermal waves.

  5. Infrared rays have a wavelength nearing …….…. Hz.


Answers: 700, longer, shorter, Infrared, 300 to 400


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FAQ (Frequently Asked Questions)

1. What is Infrared Radiation?

Ans. To define infrared radiation, these are a part of the broad electromagnetic spectrum. These rays are not visible to the human eye, but they have the following properties similar to visible light - focused, polarised and reflected.

2. What are the Types of Infrared Radiation?

Ans. There are three types of infrared radiation. They are short, medium and long infrared radiations. These waves differ based on their wavelengths.

3. What are the Uses of Infrared Radiation?

Ans. Infrared radiations have a diverse area of applications - communication, astronomy, and spectroscopy. Having prior knowledge of what is infrared radiation helps in understanding this better.