The Electromagnetic and Visible Spectra
Chapter Electromagnetic Waves Seen individually, different wavelengths appear as different colors of light. This fact can be demonstrated by using a. Within the visible light of the electromagnetic spectrum are still more wavelengths . Each wavelength is perceived by our eyes as a different color. The shorter. An obvious difference between certain compounds is their color. Thus Other common colors of the spectrum, in order of decreasing wavelength, may be.
These include radio and television waves and also microwaves. You might even have a microwave oven to cook with in your kitchen. Longer and shorter wavelengths are not visible to our eyes without special equipment. Only visible light moves in such a way that we can see it.
Visible Light Every kind of light moves at a certain wavelength. If each wavelength was laid out on a chart, it would create what is called the electromagnetic spectrum. The shorter waves would be on one end and the longer ones would be on the other. In the middle would be where visible light would end up. That is because it moves at just the right wavelength for our eyes to see it. Color Within the visible light of the electromagnetic spectrum are still more wavelengths.
Each wavelength is perceived by our eyes as a different color.
The shorter wavelengths of visible light are violet — we might call them purple. Then as the wavelengths get longer and longer, the visible light changes in color to blue, green, yellow, orange, and finally the longest, which is red. Some animals can see waveslengths of light that humans cannot.
Those waveslengths would be just outside the edges of human visible light. For example, insects can see ultraviolet waves — waves just before purple on the electromagnetic spectrum.
Visible spectrum - Wikipedia
But we are not able to see these. At the same time, there are colors of red that insects are unable to see, but that humans can. Most light that we use — like sunlight or light from a light bulb — is actually a mixture of all of the visible light wavelengths.
It is called white light. When it is mixed, it is difficult for us to separate the colors out. We just see it as useful light. But at certain times the light does get separated out. Rainbows The visible spectrum of light is often mixed together in what is called white light. We do not see each of the colors when they're mixed together. In order for that to happen, something must separate the wavelengths into their various colors.
This can happen in a rainbow. When light passes through certain materials such as water droplets from a storm or a sprinkler, the light can bend.
If it bends just right and it has to be just righteach of the different wavelengths can be seen. Because the bending has to be just right, sometimes you won't see the full arc of a rainbow.
Some of it may be missing or even appear to be hiding inside of a cloud. The colors in a rainbow appear to be red on the top and progress down through orange, yellow, green, blue, indigo and violet. Violet is another word for purple. Many scientists argue that there really isn't indigo in a rainbow. But tradition has it that the colors spell out an easily remembered name: Next time you see a rainbow, see if you can spot the indigo — a kind of blue purple.
Prisms Prisms are another way that light can be bent.
Light & Color: Facts (Science Trek: Idaho Public Television)
Prisms are actually a specially cut piece of glass or other clear material. Newton hypothesized light to be made up of "corpuscles" particles of different colors, with the different colors of light moving at different speeds in transparent matter, red light moving more quickly than violet in glass.
The result is that red light is bent refracted less sharply than violet as it passes through the prism, creating a spectrum of colors. Newton's observation of prismatic colors David Brewster Newton divided the spectrum into seven named colors: He chose seven colors out of a belief, derived from the ancient Greek sophistsof there being a connection between the colors, the musical notes, the known objects in the solar systemand the days of the week.
For this reason, some later commentators, including Isaac Asimov have suggested that indigo should not be regarded as a color in its own right but merely as a shade of blue or violet. However, the evidence indicates that what Newton meant by "indigo" and "blue" does not correspond to the modern meanings of those color words. Comparing Newton's observation of prismatic colors to a color image of the visible light spectrum shows that "indigo" corresponds to what is today called blue, whereas "blue" corresponds to cyan.
Goethe used the word spectrum Spektrum to designate a ghostly optical afterimageas did Schopenhauer in On Vision and Colors. The diagram below depicts the electromagnetic spectrum and its various regions. The longer wavelength, lower frequency regions are located on the far left of the spectrum and the shorter wavelength, higher frequency regions are on the far right. Two very narrow regions within the spectrum are the visible light region and the X-ray region.
You are undoubtedly familiar with some of the other regions of the electromagnetic spectrum. Visible Light Spectrum The focus of Lesson 2 will be upon the visible light region - the very narrow band of wavelengths located to the right of the infrared region and to the left of the ultraviolet region.
Though electromagnetic waves exist in a vast range of wavelengths, our eyes are sensitive to only a very narrow band. Since this narrow band of wavelengths is the means by which humans see, we refer to it as the visible light spectrum.
Normally when we use the term "light," we are referring to a type of electromagnetic wave that stimulates the retina of our eyes. In this sense, we are referring to visible light, a small spectrum from the enormous range of frequencies of electromagnetic radiation. This visible light region consists of a spectrum of wavelengths that range from approximately nanometers abbreviated nm to approximately nm.
Expressed in more familiar units, the range of wavelengths extends from 7 x meter to 4 x meter. Each individual wavelength within the spectrum of visible light wavelengths is representative of a particular color.
That is, when light of that particular wavelength strikes the retina of our eye, we perceive that specific color sensation. Isaac Newton showed that light shining through a prism will be separated into its different wavelengths and will thus show the various colors that visible light is comprised of. The separation of visible light into its different colors is known as dispersion. Each color is characteristic of a distinct wavelength; and different wavelengths of light waves will bend varying amounts upon passage through a prism.
For these reasons, visible light is dispersed upon passage through a prism.