What is it?
Understanding what light is will allow us to understand the way we interact with colour. So with this in mind, light is both a particle and a wave. A more precise description would be to call light a massless electromagnetic wave form particle that exists as an emission of energy and also has momentum despite being massless. Don't worry, I know this sounds rather confusing but we'll clear everything up in a bit. Just keep scrolling down!
The Photon and Electromagnetism
As perviously mentioned, light is a particle and a wave. This particle is what is known as a "photon." It is indeed massless but carries information with it as it propagates through our universe. This information is in the form of an oscillating wave that has dual properties. The first being an electric field and the second is a magnetic field. Together, these fields interact with one another at specific frequencies proportional to the energy they carry.
In the image to the right you can clearly see that the electric and magnetic waves are directly proportional to one another. The reason for this is rather complicated but the basics are fairly easy to comprehend. The biggest difference between electric and magnetic fields are that the charged particles in an electric field are stationary while these particles move at a constant velocity in a magnetic field. When these fields coincide, the charging electric field induces the magnetic field and vice versa. This interaction causes the fields to oscillate forming the wave that we see. [1]
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The Formation of Colour
Once the formation of the wave has been established, its specific frequency determines if we see light or nothing at all. Perhaps surprisingly, the light humans can see is only a very small proportion of the total wave frequencies photons can exist in. Furthermore, it is the frequency of the wave that will determine what colour our eyes will see.
Our eyes can see light if the peaks of the wave form are between 350 and 800 nanometres. A nanometre is one billionth of a metre. Written out that looks like this "0.000000001m" or this "1×10−9m." After or before this distance our eyes will only see darkness, but through specialized machines we can augment the waves into colours that are perceivable. In many instances this method is used to see information that would have previously been obscured to us. Examples of this are ultrasounds, X-rays and various types of spectroscopy. [2]
The image below is a perfect example of this as it uses infrared spectroscopy to show star formation within gas and dust clouds. The information is invisible within the normal visual spectrum.
The image below is a perfect example of this as it uses infrared spectroscopy to show star formation within gas and dust clouds. The information is invisible within the normal visual spectrum.
Click below to see how our eyes interpret these waves and how we see colours.
References:
[1] http://missionscience.nasa.gov/ems/02_anatomy.html
[2] Interview with Dr. James H. Watt of 700 Main X-ray and Ultrasound
Images:
References are beneath every image and here in order from left to right, top to bottom.
http://hubblesite.org/newscenter/archive/releases/2007/16/image/a/format/xlarge_web/
https://en.wikipedia.org/wiki/Electromagnetic_radiation#/media/File:Electromagneticwave3D.gif
https://chrisparkins.wordpress.com/2013/09/01/the-colour-of-light/
https://www.spacetelescope.org/images/heic1406c/
http://www.euhou.net/index.php/exercises-mainmenu-13/classroom-experiments-and-activities-mainmenu-186/179-observations-of-various-spectra-with-a-home-made-spectroscope
[1] http://missionscience.nasa.gov/ems/02_anatomy.html
[2] Interview with Dr. James H. Watt of 700 Main X-ray and Ultrasound
Images:
References are beneath every image and here in order from left to right, top to bottom.
http://hubblesite.org/newscenter/archive/releases/2007/16/image/a/format/xlarge_web/
https://en.wikipedia.org/wiki/Electromagnetic_radiation#/media/File:Electromagneticwave3D.gif
https://chrisparkins.wordpress.com/2013/09/01/the-colour-of-light/
https://www.spacetelescope.org/images/heic1406c/
http://www.euhou.net/index.php/exercises-mainmenu-13/classroom-experiments-and-activities-mainmenu-186/179-observations-of-various-spectra-with-a-home-made-spectroscope