The electromagnetic spectrum consists of many different types of waves, from radio waves to gamma rays. One of the most familiar sections of the EM spectrum is visible light. Visible light allows us to see colors in our everyday lives, and although it's big in our world, it's very small on the EM spectrum. In fact, visible light is the smallest section of the spectrum!
Visible light is the different colors of the rainbow, and each color has a different wave frequency. The frequencies can range from 4 x 10^14 Hz (red) to 7.5 x 10^14 Hz (violet). Each color also has a different wavelength; red, the lowest, has a wavelength of 400 nanometers, and violet, the highest, has a wavelength of 700 nanometers.
When we see color, some of the waves from the Sun are reflected back to us (the color we see), and some are absorbed. If all of the colors in the spectrum were to be combined, white light would be produced. To see color, white is emitted, and then a color, maybe green, is reflected. The other colors are absorbed by the "green" object.
Visible light is used a lot in our everyday lives. Lasers are made using light, as well as infrared (waves below the frequency of red) and ultraviolet (waves above the frequency of violet) technology. Light allows nature lovers to see sunsets and rainbows. Studies have shown that a yellow-green color is best seen by humans, so many emergency vehicles and construction uniforms are changing to this color. However, there are some safety concerns and "let-downs" of visible light. Some lasers are very powerful and can be harmful to the eyes. Lightbulbs, which emit this powerful yellow-green color, are very strong at the source and can hurt our eyes, and the radiance dies down as you get further away from the source.
This is just a background of one section of the electromagnetic spectrum. For more information, visit some of the websites below.
Both pictures taken from "The Electromagnetic Spectrum" from NASA
For more information/Bibliography:
"Electromagnetic Spectrum" by HyperPhysics
"Visible Light Waves" by NASA (http://science.hq.nasa.gov/kids/imagers/ems/visible.html)
"Laser Safety Training Guide" from Princeton University (http://web.princeton.edu/sites/ehs/laserguide/index.htm)
1 comment:
I feal that I definatly know more about visible light than any other section of the EM spectrum. You did a good job at explaining how we see the actual colors in objects. I had almost forgoten about that. I also liked how you had several links at the bottom of the post that could allow people to learn more about visible light.
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