Astronomy 100 - Problem Set 4

Due: Tuesday 4 March 2008
Name:

Fill in the box with the correct answer (answers should be just a few words or a number).

  1. Consult figure 6-3 in your book. Is it possible to see out into space from the ground using X-ray light?

  2. According to figure 7-8 in your book, the spectral lines of which element will be most prominent in a star which has a surface temperature of 5000 Kelvins?

  3. WFCR FM broadcasts radio light at a frequency of 88.5 MHz (MHz = megahertz = 1 million cycles per second). What is the wavelength of the electromagnetic waves that carry the WFCR signal? Express your answer in meters.

  4. What type of photon from the electromagnetic spectrum (radio, infrared, visible, ultraviolet,...) carries the most energy?

  5. Consult Figure 7-9 in your book. What spectral class of star shows the most prominent absorption lines of hydrogen gas?

  6. Consider a blackbody at a temperature of 1000 Kelvins. What is the peak wavelength of light emitted by such a blackbody?

  7. In what region of the electromagnetic spectrum (radio, infrared, visible, ultraviolet,...) is your answer for #6?

  8. Consult the Figure on page 147 in your book. What wavelength of radiation is emitted when an electron drops from the 3rd to the 2nd energy level in a Hydrogen atom?

  9. Consider an electron in an atom which can jump (transition) between different energy levels. Transition A produces light with a wavelength of 600 nm. Transition B involves half as much energy as A. What wavelength light does it produce?

  10. In the laboratory you measure that a spectral line has a wavelength of 700 nm. You observe a distant galaxy and find the same spectral line, but it appears at a wavelength of 710 nm. Use the Doppler equation to find the velocity of this galaxy toward or away from us. A "+" sign should appear in your answer if the galaxy is moving away from us. A "-" sign means it is moving toward us.