|The Electromagnetic Spectrum|
Johann Ritter suspected “invisible” light on the opposite (blue) end of a spectrum and used paper soaked with silver chloride to detect it. Thomas Young confirmed the wave nature of light (that light moves like waves similar to ocean waves) by examining diffraction patterns through slits.
Michael Faraday and James Maxwell collaborated together to theorize the electromagnetic nature of light – that is changing the electric current in the wave alters its magnetic field. The image below (don’t laugh, I’m still learning Adobe Illustrator!) demonstrates how the magnetic portion of this wave is 90o to the electric portion of the wave – hence ‘electromagnetic.’
Experimenting with “Maxwellian Waves,” Heinrich Hertz discovered radio waves. Wilhelm Rontgen discovered X-Rays while seemingly serendipitously experimenting with electric current through cardboard tubes with exposed film he had on the other end of the room – he saw the bones of his hand.
It wasn’t until Albert Einstein, winning the Nobel Prize for discovering the photoelectric effect, that the wave-particle duality of electromagnetic waves was understood.
Eventually, a tool was created in the form of the electromagnetic spectrum.
As a starting point for understanding the spectrum, visible light covers only a small part – 400 nanometers (blue) to 700 nanometers (red).
The image below is a graph from the Chandra website demonstrating the entire electro-magnetic spectrum. Notice that only a very small portion of this spectrum (in the middle) is made up of visible light.