Review Questions
What distinguishes one type of electromagnetic radiation from another? What are the main categories (or bands) of the electromagnetic spectrum?
What is a wave? Use the terms wavelength and frequency in your definition.
Is your textbook the kind of idealized object (described in section on radiation laws) that absorbs all the radiation falling on it? Explain. How about the black sweater worn by one of your classmates?
Where in an atom would you expect to find electrons? Protons? Neutrons?
Explain how emission lines and absorption lines are formed. In what sorts of cosmic objects would you expect to see each?
Explain how the Doppler effect works for sound waves and give some familiar examples.
What kind of motion for a star does not produce a Doppler effect? Explain.
Describe how Bohr’s model used the work of Maxwell.
Explain why light is referred to as electromagnetic radiation.
Explain the difference between radiation as it is used in most everyday language and radiation as it is used in an astronomical context.
What are the differences between light waves and sound waves?
Which type of wave has a longer wavelength: AM radio waves (with frequencies in the kilohertz range) or FM radio waves (with frequencies in the megahertz range)? Explain.
Explain why astronomers long ago believed that space must be filled with some kind of substance (the “aether”) instead of the vacuum we know it is today.
Explain what the ionosphere is and how it interacts with some radio waves.
Which is more dangerous to living things, gamma rays or X-rays? Explain.
Explain why we have to observe stars and other astronomical objects from above Earth’s atmosphere in order to fully learn about their properties.
Explain why hotter objects tend to radiate more energetic photons compared to cooler objects.
Explain how we can deduce the temperature of a star by determining its color.
Explain what dispersion is and how astronomers use this phenomenon to study a star’s light.
Explain why glass prisms disperse light.
Explain what Joseph Fraunhofer discovered about stellar spectra.
Explain how we use spectral absorption and emission lines to determine the composition of a gas.
Explain the results of Rutherford’s gold foil experiment and how they changed our model of the atom.
Is it possible for two different atoms of carbon to have different numbers of neutrons in their nuclei? Explain.
What are the three isotopes of hydrogen, and how do they differ?
Explain how electrons use light energy to move among energy levels within an atom.
Explain why astronomers use the term “blueshifted” for objects moving toward us and “redshifted” for objects moving away from us.
If spectral line wavelengths are changing for objects based on the radial velocities of those objects, how can we deduce which type of atom is responsible for a particular absorption or emission line?