Infrared Radiation - Electromagnetic Waves

Infrared radiation or IR also referred to as infrared, is a region of the electromagnetic radiation spectrum where the range of wavelengths is from about 700 nanometers to 1 millimetre. It is a type of radiant energy that is invisible to human eyes but that we can feel as heat. Depending on the wavelength and frequency, infrared is commonly divided into five categories: near-wavelength, short-wavelength, mid-wavelength, long-wavelength and far-infrared.

What are Infrared Radiations?

The word infrared means below red. Red light has the longest wavelength that our eyes can see but infrared waves cannot be seen by the eye.

  • Infrared radiations are also referred to as heat or thermal waves or electromagnetic waves. This is because they have a heat-inducing property. Sometimes infrared rays are used in applications where heat production is required like in infrared heaters or for therapeutic purposes where a patient requires physical therapy.
  • These waves have a wavelength range between 710 nm to 1 mm. Sometimes infrared rays themselves are classified as near infrared and far infrared rays.
  • Near-infrared rays are used in electronic applications like TV remote sensors and photography. Their applications can be somewhat similar to visible light applications since their wavelength ranges are close.
  • Far infrared rays are more thermal in nature. Anything generating heat gives out far infrared radiation. Even the human body (at \(37^{\circ}C\) ) gives off infrared radiations of around 800 nm wavelength.
Infrared Radiation

Infrared Radiation from the Sun

Infrared Radiation Wavelength

We already know that the wavelength of the infrared radiation is between 700 nm to 1 mm, which is between the red limit of the visible spectrum. But following is the classification of bands based on the spectral range 1µm and 50µm:

  1. 1µm to 3µm which is known as the band I or Short Wave Infrared
  2. 3µm to 5µm which is known as the band II or Middle Wave Infrared
  3. 8µm to 14µm which is known as the band III or Long Wave Infrared

Infrared Rays Uses

Following are the uses of infrared rays:

  1.  Communications: Infrared lasers are used for free space optical communications as these are relatively inexpensive. These also find applications in the areas that are densely populated.
  2. Spectroscopy: Infrared vibrational spectroscopy is used for identifying the molecules by analysing their bonds as the molecule vibrates at different frequencies. The unit used to express the radiation is cm-1.
  3. Astronomy: Optical components like mirrors, lenses and digital detectors are used to study the objects that are in space. These objects glow when they are exposed to the radiated heat.

Applications of Infrared Radiation

Infrared light can also term has thermal light. The light near a campfire or even the light of the sun, these kinds of lights also emit some thermal energy which causes you to feel the heat. Infrared heaters also come under this where they use infrared radiation to generate thermal energy.

Extended Reading List

Stay tuned with BYJU’S to read more about infrared radiation and other electromagnetic waves that form the electromagnetic spectrum and their wide range of applications with interactive videos to make learning simple.

Frequently Asked Questions on Infrared Radiation

List a few properties of infrared radiation?

Following are a few properties of infrared radiation:

  1. Infrared radiation, like all radiation, travels at a speed of 299,792,458 meters per second.
  2. Infrared light can exhibit both wave and particle nature at the same time.
  3. Depending on the nature of the material that infrared radiation strikes, it can either be absorbed or reflected.
  4. Infrared radiation increases the thermal energy in particles.

List a few medicinal effects of infrared radiation?

A few medicinal effects of infrared radiation are as follows:

  • Used to reduce the inflammation of throat, ear and nose
  • Used as an aid in stress management
  • Reduces pain arthritis
  • It eases kidney function

How do we experience infrared radiation on a daily basis?

Infrared is a type of radiant energy that is invisible to the eyes and we can only feel it in the form of heat. All objects in the universe emit some level of IR radiation. Sun and fire are among the most obvious source of infrared radiation.

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