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# homework1 - described by a rather complicated mathematical...

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Physics 20A: Introduction to Astronomy Homework assignment #1 Due October 6 1. Textbook, p. 20, question #6. 2. Textbook, p. 20, question #8. 3. An electromagnetic wave has a frequency of 300 Megahertz. What is its wavelength? 4. Two objects, A and B, have the same size, and both are emitters of black-body radiation. Object A has a surface temperature of 8000 K while object B has a surface temperature of 4000 K. a) Which object emits more electromagnetic radiation? (That is, which object has a higher luminosity?) b) What is the ratio of the luminosities of the two objects? c) Which object has a redder color? d) Draw a simple plot showing the spectra of the 2 objects, similar to the one shown on p. 26 of your textbook. Label the curves for object A and B, and use Wien’s law to determine the wavelength where each spectrum will have its peak value. Don’t worry about the exact shape of the two curves, since they are
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Unformatted text preview: described by a rather complicated mathematical function that’s not given in your textbook– just sketch it out in a way that shows what the approximate shape of the spectrum should look like. Be sure to label the axes of your plot and show numerical values for the wavelengths where the two spectra have their peak values. Following the example on p. 26 of your textbook, use wavelength units of Ångstroms. 5. Textbook, p. 36, question #23. 6. Textbook, p. 59, question #2. 7. Textbook, p. 59, question #3. 8. Textbook, p. 59, question #14. 9. (a) Why are the best optical telescopes located on high mountaintops in deserts or remote islands? What are the advantages of these locations for astronomical observing, and why would Irvine not be a good site to build a research observatory for optical astronomy? (b) Where are X-ray telescopes located, and why? 10. Textbook, p. 59, question #24. 1...
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## This note was uploaded on 04/16/2008 for the course PHYS 20A taught by Professor Staff during the Winter '02 term at UC Irvine.

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