The graph below the Sun's UV spectrum shows the same information in a more quantitative format. As with the other spectra, the x-axis indicates the energy of the observed light. However, instead of indicating the observed energies with light bands, the graph shows the intensity of the radiation on the y-axis. While the graph isn't as colorful as those shown in a "photographic" format, this representation tells us much about the UV emission of the Sun. Compare the two representations of the solar UV spectrum.
Notice that where the first spectrum shows a bright line, the second shows a peak in the graph. This type of spectrum shows us not only where the Sun emits light, but also gives a measure of how much light is emitted as a function of energy. The above examples have been of emission spectra; however, there is another type called "absorption spectra.
Essentially, the spectrum that we observe is the continuous spectrum with dark spots where the gas has "picked out" the continuum. The spectrum above shows a continuum spectrum absorbed by an gas. The dark bands correspond the exact wavelengths of lights we would see in an emission spectrum, and can similarly be used to identify the characteristic spectrum of various elements.
Here is another example of an absorption spectrum. This one is presented on many different lines because if we laid this out a a single line it would stretch across the width of your browser many, many times. The incredible detail in this spectrum is due to the high resolution of the detector used to record it. When the light leaves the surface of the Sun, it is very nearly a continuous spectrum. However, as it passes through the Sun's atmosphere, gasses present in that atmosphere absorb specific wavelengths of light, leaving the pattern seen in the spectrum above.
Credit: U. Fish and Wildlife Service. A spectrum is simply a chart or a graph that shows the intensity of light being emitted over a range of energies. Have you ever seen a spectrum before? Nature makes beautiful ones we call rainbows. Sunlight sent through raindrops is spread out to display its various colors the different colors are just the way our eyes perceive radiation with slightly different energies. Spectroscopy can be very useful in helping scientists understand how an object like a black hole, neutron star, or active galaxy produces light, how fast it is moving, and what elements it is composed of.
Spectra can be produced for any energy of light, from low-energy radio waves to very high-energy gamma rays. Each spectrum holds a wide variety of information. For instance, there are many different mechanisms by which an object, like a star, can produce light. Each of these mechanisms has a characteristic spectrum. White light what we call visible or optical light can be split up into its constituent colors easily and with a familiar result: the rainbow.
All we have to do is use a slit to focus a narrow beam of the light at a prism. This setup is actually a basic spectrometer.
The resultant rainbow is really a continuous spectrum that shows us the different energies of light from red to blue present in visible light. Continuous spectra are produced by all incandescent solids and liquids and by gases under high pressure. A gas under low pressure does not produce a continuous spectrum but instead produces a line spectrum, i. If the gas is made incandescent by heat or an electric discharge, the resulting spectrum is a bright-line, or emission, spectrum, consisting of a series of bright lines against a dark background.
A dark-line, or absorption, spectrum is the reverse of a bright-line spectrum; it is produced when white light containing all frequencies passes through a gas not hot enough to be incandescent. It consists of a series of dark lines superimposed on a continuous spectrum, each line corresponding to a frequency where a bright line would appear if the gas were incandescent.
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