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Chapter 4: Light and the Electromagnetic Spectrum
What is Spectroscopy?
When a white beam of light strikes a prism, a beam of multicolored light emerges on the opposite side. What is it about light that allows it to be separated into colors and why is this so important for studying astronomy? Visit the site linked above to unravel the mystery of spectroscopy.
Study the materials on this site and write a brief essay distinguishing among continuous, dark-line, and bright-line spectra. Be sure to use ideas or terms not used in the textbook.
Visit the What is Spectroscopy? web site
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Radiation Laws
In the late nineteenth century, scientists made theoretical calculations of the radiation that would be emitted from an object that absorbed all wavelengths completely. Such an object was called a blackbody, and the radiation it emitted was called blackbody radiation.
Wien's displacement law relates the temperature of a radiant body and the wavelength of the peak of the radiation distribution. Do the following: 1) Use the first graph on the site to determine the wavelenght of the peak radiation for a 4000K object. 2) Use Wien's law to determine the same thing more accurately. 3) Check the applets on this page.
Visit the Radiation Laws web site
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The Use of Filters on Telescopes
The Crab nebula is what remains of an exploded star. This site shows how "the Crab" looks when different filters are used on a telescope.
View the Crab nebula through each of the three filters and with no filter. 1) Describe similarities between the views. 2) Go to the "Let's Discuss . . ." page. Which filter might you employ to view the hot central portion of the Crab? 3) Use what you have learned in this chapter to explain why color filters would change the image so much.
Visit the The Crab Nebula Through Filters web site
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