Middle Georgia State University

Course title: ASTR 1010K

Chapter 4 Homework

1)A blackbody glowing with which of the following colors is hottest?

2. The spectrum of which of the following objects will show a blueshift?

3. What is Wien’s law? How could you use it to determine the temperature of the star’s surface?

4. Using Wien’s law and the Stefan-Boltzmann law, state the changes in color and intensity that are observed as the temperature of a hot, glowing object increases.

5. What is an element? List the names of five different elements, and briefly explain what makes them different from each other.
6. How are the three isotopes of hydrogen different form each other?

7. Explain how the spectrum of hydrogen is related to the structure of the hydrogen atom.

8.  What is the Doppler shift, and why is it important to astronomers?

9. Approximately how many times around the world could a beam of light travel in 1 s?

10. The bright star Regulus in the constellation of Leo (the Lion) has a surface temperature of 12,000 K. Approximately what is the dominant wavelength (?max) of the light that is emits?

11. The bright star Procyon in the constellation of Canis Minor (the Little Dog) emits the greatest intensity of radiation at a wavelength ?max= 445 nm. Approximately what is the surface temperature of the star in kelvins?

12. In the spectrum of the bright star Rigel, H? is observed to have a wavelength of

656.331 nm. Is the star coming toward us or moving away from us? How fast?

13. Imagine driving down a street toward a traffic light. How fast would you have to go so

that the red light (700 nm) would appear green (500 nm)? What fraction of the speed of light c (c= 300,000 km/s) is this velocity?