Frisco Inspection Company owner Jeff Cardile, president of Lookout Capital Inspections answers the question, What is Infrared?  Part 2

Missing Insulation

Today, we are going to talk about Frequency and Color.

How do we see?  When light falls on objects a portion of the light is absorbed and a portion of the light is reflected.  When light falls on a tree, all of the visible light is absorbed except for the green portion of the visible spectrum, which is reflected.  We see the light that is reflected and our eyes come to the conclusion that the tree is green.  Similar,  a black shirt absorbs all of the spectrum and is seen as black.  A white shirt reflects all of the spectrum and is seen as white.  The important question is what happens to the absorbed light?  Atoms absorb the energy and the electrons raise to a higher energy level and exit.  When the electrons exit they want to return to there normal state. They release there stored energy as electromagnetic energy.  This energy is emitted slowly.

The structure of the atoms and their valence shells determines the wavelength of the emitted energy.  The greater the temperature, the higher the frequency of light omitted.  Example, iron glows red, then yellow, than white as it gets hotter.  Due to the structure of atoms and the low temperatures of common objects, most of the absorbed energy is released in the infrared portion of the electromagnetic spectrum.  When objects are heated they release heat as infrared radiation.  Now, how this energy is stored and/or emitted is dependent solely on the material emitting or absorbing the energy.

There are 3 different types of Infrared Radiation

1. Near Infrared: This is the area of the spectrum closet to visible light, just below red light, and has a wavelength of .7-1.3 microns.
2. Mid-Infrared: This the area of the spectrum used by electronic devices. (ie. television remote controls).  These have a wavelength between 1.3-3 microns.
3. Thermal Infrared: This is the area of the spectrum that is used for Thermal Imaging because this is where light is being emitted from an object compared to being reflected.  The emitted light is energy that comes from the atoms of the object not the energy that is being reflected by the object. These have a wavelength between 3-30 microns.

In our next blog we will discuss the physics of Heat: Conduction, Convection, and Radiation

Frisco Inspection Company is owned by Jeff Cardile.  Jeff is a Certified Thermographer.  Lookout Capital Inspections is proud to be a leader in the inspection industry.  Call Jeff at (469) 853-7336 for any of your inspection needs.