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How do frequency and wavelength affect the properties of light?

How do frequency and wavelength affect the properties of light?


The visible light spectrum makes up 100% of all optically observable light to humans.


But how is the spectrum affected by a change in frequency and wavelength?


Here, we look at the properties of light and how it interacts differently with our natural environment.





What are the classifications of light?


To start this discussion, it would be useful for us to have a list of all the classifications of light in the electromagnetic spectrum.


Starting at extremely high frequency (300EHz) but low wavelength (1pm) electromagnetic radiation would be gamma rays.


This is followed by hard X-rays at 30EHz-3EHz and 10-100pm, soft X-rays at 3Phz-300PHz and 1-10nm, and ultraviolet light at 3PHz-300THz and 10-100nm.


Then comes the visible spectrum between 300THz-30THz and 1 micrometer to 100 micrometers, followed by infrared radiation at 30THz-3THz and 10-100micrometers.


Finally, there are microwaves and radio waves at wavelengths between 100,000km and 1mm and of frequencies of around 300GHz to 3Hz.




What trends are seen when moving from one side of the spectrum to the other?


One of the most telling properties of electromagnetic radiation is the energy carried in a wave.


In a high frequency, low wavelength waveform, there is a massive amount of energy stored in the wave.


This energy travels through the wave as kinetic energy due to the wave-particle duality of electromagnetic radiation.


Imagine the increased distance that a high frequency wave is travelling in comparison to a low frequency wave, due to there being many more peaks and troths present over the same distance. This explains how there is more energy in said waveform.



What happens when the energy increases?


With this increase in energy comes another property that follows an inverse trend.


As the energy increases alongside frequency, its ability to penetrate solid matter decreases.


This is explained by the Beer-Lambert Law, which states that as a wave penetrates further into a material, its intensity is decreased.


This would of course be due to wave-particle interactions, where the light is absorbed by the electron shells of atoms and molecules.


This penetrative property is best visualised by gamma radiation. This is an extremely high-frequency, high-energy and low-wavelength electromagnetic radiation.


If able to enter the human body, it would do massive damage to our internal organs and would cause cancer or even death. However, in reality it does not have the ability to penetrate through a piece of paper.