ASTR1010, Fall 2003
Study Guide for Test #2
This test will cover chapters 3,4,5
Math problems will resemble the problems gone over in class and could include other eq, such as diffraction limited resolution and E = hf.
Chapter 3;
Light/Electromagnetic Radiation
- Why is it so important to astronomy?
- Define "electromagnetic radiation"
- What are the two ways in which light can behave?
- Define "wave"
- What are the two kinds of waves?
- Which kind of wave is light? Sound?
- Label and define the properties of a transverse wave (as per Figure 3.3)
- What are the two units of length usually used to describe visible light? How are they defined?
- What equation relates the wavelength, frequency, and velocity of a wave?
- What is the speed of all light waves travelling in a vacuum?
- Define "diffraction"
- Define "interference." What happens when constructive interference occurs? What happens when destructive interference occurs?
- Define "polarization"
- The phenomena of diffraction, interference, and polarization are examples of light behaving as a ______?
- What is the wavelength range of visible light (ie the wavelengths of light that human eyes can detect)?
- What is white light made out of?
- What is the function of a prism?
- What wavelengths correspond to the various colors of visible light?
- Why are our eyes sensitive to this particular wavelength range?
- Do light waves need a medium to travel through? Do sound waves?
- What causes an electric field?
- What causes a magnetic field?
- What makes up an electromagnetic wave?
- Can light travel instantaneously (ie with infinite speed)?
- Know the wavelength and frequency ranges corresponding to the various kinds of light (Fig 3.9)
- Be able to compare these ranges for different kinds of light (ie Radio waves have lower frequencies than optical waves).
- Which kinds of light can penetrate the Earth's atmosphere?
- What attributes of our atmosphere block which kinds of light?
- What is temperature a measure of?
- How is the Kelvin temperature scale defined?
- Define "absolute zero"
- What is "intensity"?
- Describe the Black Body/Planck curve
- What attribute of an object defines what its Black Body curve will look like?
- How does one construct a Black Body curve?
- Do stars emit ideal Black Body curves? If not, what makes them different from ideal curves?
- What colors are exhibited by which temperatures?
- What is the equation for Wien's Law? What do each of these terms mean?
- What is the equation for Stefan's Law? What do each of these terms mean?
- What is the Doppler Effect?
- What is meant by redshifting and blueshifting?
- Under what circumstances will light be blueshifted or redshifted?
- Define "radial motion" and "transverse motion"
- The Dopper Effect depends on which kind of motion?
Chapter 4:
Spectroscopy and the particle nature of light
- Define "spectroscopy"
- What does an emission spectrum look like?
- What does an absorption spectrum look like?
- What does a continuous spectrum look like?
- Why do we say that spectral lines act as fingerprints?
- What are Kirchoff's 3 Laws?
- What are Fraunhofer lines?
- Describe the Bohr model of the hydrogen atom and the various components of it.
- Describe the modern view of the atom
- What atoms are best described by the Bohr model?
- Define "orbital" or "energy level"
- Define "ground state"
- Define "excited state"
- Define ion, positive ion, negative ion
- According to the Bohr model, how is an emission line created?
- According to the Bohr model, how is an absorption line created?
- What equation relates energy and frequency?
- What is a photon? At what speed do photons travel?
- Can any other particle travel as fast as photons?
- What does "quantized" mean? How does it apply to electron energy levels and light?
- Define "Balmer series." This is visible in what wavelength range?
- Define "Lyman series." This is visible in what wavelength range?
- What is cascading?
- Why are the spectra of heavier atoms and molecules more complex than the spectra of single, lighter atoms?
- Define "molecule"
- How is the presence or lack of an atom's or molecule's spectral lines indicative of the temperature of a gas?
- What is meant by "broad spectral lines"?
- Describe 5 effects/conditions that will broaden specral lines
- Can theses effects/conditions be differentiated by only looking at the broaden lines they produce? Can two or more of these effects occur at once?
Chapter 5:
Telescopes
- Define "telescope"
- How does a reflecting telescope work?
- How does a refracting telescope work?
- Define "refraction"
- Define "focal length"
- What is magnification?
- What is resolution?
- Does an eyepiece improve magnification? resolution?
- Define "chromatic aberration"
- What are 4 advantages of reflecting telescopes over refracting?
- Are modern large optical telescopes reflectors or refractors?
- Describe the prime focus, Newtonian, Cassegrain, and Coude designs of reflecting telescopes.
- What is a Coude room? Why is the Coude telescope design required for a Coude room?
- What three designs does the Palomar telescope incorporate?
- Define "field of view." What units do we measure it in?
- Define "coma." How is it corrected?
- What is a photometer? What kind of research is it good for?
- What is a spectrometer?
- How does the observe brightness of an object relate to the diameter of a telescope?
- How does one increase the resolving power of a telescope?
- What is the equation for diffraction limited resolution?
- What keeps ground-based telescopes from achieving diffraction limited resolution?
- Define "seeing"
- Describe a "seeing disk"
- What are some ways to combat atmospheric effects?
- What are some locations that are good for overcoming atmospheric effects?
- What is a CCD? What is it used for in astronomy?
- How does a CCD work?
- What are the advantages of CCDs over photgraphic plates?
- Why is image processing via computers helpful?
- What are biases? flats? darks? What do they record/reveal?
- What are "active optics"? What are they used for?
- What are "adaptive optics"? What are they used for?
- How long has radio astronomy been around?
- Who is Karl Jansky? What work is he known for?
- Can radio astronomy be done from the ground?
- Describe a general radio telescope.
- What are the reasons that radio telescopes are very large in size?
- Why can radio telescopes have rougher surfaces than smaller wavelength telescopes?
- What are the benefits of observing radio waves?
- What is the main drawback of radio astronomy? How is it combatted?
- Define "interferometry"
- What is the primary benefit of using interferometry?
- What is the VLA? What kind of light does it observe?
- What is CHARA? What kind of light does it observe?
- What is HST? What wavebands does it study?
- What are the advantages and disadvantages of HST vs. ground based telescopes? (compare size, resolution, ease of maintenance, atmospheric effects, design)
- What are infrared telescopes like?
- Can infrared astronomy be done from the ground?
- What can infrared light penetrate that visible light can't?
- Why do infrared telescopes have to be strongly cooled?
- What is IRAS? Why did it end?
- Where must all ultraviolet astronomy be done? Why?
- What are ultraviolet telescopes like?
- What are IUE, EUVE, and FUSE? Which are still operating?
- What wavebands are studied in high energy astronomy?
- Where must all high energy astronomy be done from? Why?
- Why must high energy telescopes be different than optical telescopes?
- How do gamma ray telescopes work?
- What is CGRO? Is it still operating?
- How do X-ray imaging telescopes work?
- What kind of light does/did the Einstein Observatory, Chandra, and RXTE observe? Which creates images instead of just collecting light? Which are still operating?
Equations:
You are expected to memorize the following equations. Know what each term means, what units are used, and be able to work problems with these equations. You do not have to memorize the values of the constants (ie c, h, s), I will provide these for you.
Stefan's Law
Wien's Law
E = h*f
v = f*l
for light; c = f*l
f = 1/P
Diffraction limited resolution