Now what!? LOL!
Monday, January 31, 2011
Astronomy Problems 561: Practice Problems on Stellar Spectra 1/26/2011
1. Define the following wave properties: period, wavelength, amplitude, frequency.
2. Why is light referred to as an electromagnetic wave?
3. In what regions of the electromagnetic spectrum is the atmosphere transparent enough to allow observations from the ground?
4. What is a blackbody? What are the main characteristics of the radiation it emits?
5. What is the wavelength of a 1000kHz “AM 100” radio signal?
6. What is the wavelength of a 2eV photon?
7. The blackbody emission spectrum of object A peaks in the ultraviolet region of the spectrum of the electromagnetic spectrum, at a wavelength of 200nm. That of object B peaks in the red region at 650nm. Which object is hotter, and according to Wien’s law, how many times hotter is it? According to Stefan’s law, how many times more energy per unit area does the hotter body radiate per second?
8. Normal human body temperature is about 37o C. What temperature is it in Kelvins? What is the peak wavelength emitted by a person with this temperature? In what part of the spectrum does this lie? Estimate the heat power output of the human body.
9. According to the Stefan-Boltzmann law, how much energy is radiated into space per unit time by each square meter of the Sun’s surface? If the Sun’s radius is 696,000km what is the total power output of the Sun?
10. What is a continuous spectrum? An absorption spectrum? An emission spectrum?
11. What is the normal condition for electrons in an atom? What are orbitals? What is an excited atom?
12. What information is contained in an emission or absorption spectrum?
13. A distant galaxy is receding from the Earth with a radial velocity of 3000km/s. At what wavelength would its Lyα line be received by a detector above the Earth’s atmosphere?
2. Why is light referred to as an electromagnetic wave?
3. In what regions of the electromagnetic spectrum is the atmosphere transparent enough to allow observations from the ground?
4. What is a blackbody? What are the main characteristics of the radiation it emits?
5. What is the wavelength of a 1000kHz “AM 100” radio signal?
6. What is the wavelength of a 2eV photon?
7. The blackbody emission spectrum of object A peaks in the ultraviolet region of the spectrum of the electromagnetic spectrum, at a wavelength of 200nm. That of object B peaks in the red region at 650nm. Which object is hotter, and according to Wien’s law, how many times hotter is it? According to Stefan’s law, how many times more energy per unit area does the hotter body radiate per second?
8. Normal human body temperature is about 37o C. What temperature is it in Kelvins? What is the peak wavelength emitted by a person with this temperature? In what part of the spectrum does this lie? Estimate the heat power output of the human body.
9. According to the Stefan-Boltzmann law, how much energy is radiated into space per unit time by each square meter of the Sun’s surface? If the Sun’s radius is 696,000km what is the total power output of the Sun?
10. What is a continuous spectrum? An absorption spectrum? An emission spectrum?
11. What is the normal condition for electrons in an atom? What are orbitals? What is an excited atom?
12. What information is contained in an emission or absorption spectrum?
13. A distant galaxy is receding from the Earth with a radial velocity of 3000km/s. At what wavelength would its Lyα line be received by a detector above the Earth’s atmosphere?
Sunday, January 30, 2011
Welcome to the blog for the Texas A&M-University Commerce Astronomy Problems 561 course. Feel free to post questions, thoughts about the various projects we work on, and experiences on the various astronomy sites, blogs and forums you encounter. If you find interesting astronomy related resources and news articles, this is the place to post them. Enjoy!
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