5 Written questions
5 Matching questions
- Which of the following statements about X rays and radio waves is not true?
A) Neither X rays nor radio waves can penetrate the earth's atmosphere.
B) X rays have shorter wavelengths than radio waves.
C) X rays and radio waves are both forms of light, or electromagnetic radiation.
D) X rays have higher frequency than radio waves.
E) X rays have higher energy than radio waves.
- If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?
A) We must actually be observing moons orbiting the planet in opposite directions, not the planet itself.
B) The planet is rotating.
C) The planet is in the process of falling apart.
D) The planet is in the process of formation.
- Briefly explain why spectral lines are useful in determining the chemical composition of their source.
- You observe the same spectral line in two stars that are identical in every way except that one rotates faster than the other. How does the spectral line differ between the two?
A) There is no difference.
B) The line in the faster rotating star is blueshifted.
C) The line in the faster rotating star is redshifted.
D) The line in the faster rotating star is broader.
E) The line in the faster rotating star is narrower.
- The energy levels for electrons vary from one element to another.
- a D) The line in the faster rotating star is broader.
- b True
- c A) Neither X rays nor radio waves can penetrate the earth's atmosphere.
- d B) The planet is rotating.
- e Every chemical element has a unique set of atomic energy levels and therefore a unique set of spectral lines. Thus, by identifying spectral lines, we can identify the elements that produced them.
5 Multiple choice questions
- D) The planet is rotating.
- The most common isotope of gold contains 79 protons and 118 neutrons. If it is neutral, it also contains 79 electrons. If the gold is triply ionized instead, it is missing 3 electrons and so has only 76 electrons.
- D) it reflects green light and absorbs other colors.
5 True/False questions
The study of energy levels in atoms is called
A) special relativity.
B) general relativity.
C) quantum mechanics.
D) classical mechanics.
E) particle physics. → C) ionized.
Oxygen has atomic number 8. How many times must an oxygen atom be ionized to create an O+5 ion, and how many electrons will the ion have?
A) It must be ionized three times; it now has five electrons.
B) It must be ionized five times; it now has five electrons.
C) It must be ionized five times; it now has three electrons.
D) It doesn't have to be ionized; it just needs to gain five protons.
E) It doesn't have to be ionized; it already has only three electrons. → False
From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 121.8 nm. What can we conclude?
A) The star is moving toward us.
B) The star is moving away from us. C) The star is getting hotter.
D) The star is getting colder.
E) The "star" actually is a planet. → True
Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: Think about the laws of thermal radiation.)
A) The red star is more massive than the blue star.
B) The blue star is more massive than the red star.
C) The blue star is farther away than the red star.
D) The blue star has a hotter surface temperature than the red star.
E) The red star has a hotter surface temperature than the blue star. → C) several kilometers
Suppose that two stars are identical in every wayfor example, same distance, same mass, same temperature, same chemical composition, and same speed relative to Earthexcept that one star rotates faster than the other. Spectroscopically, how could you tell the stars apart?
A) The faster rotating star has wider spectral lines than the slower rotating star.
B) The faster rotating star will have an emission line spectrum while the slower rotating star will have an absorption line spectrum.
C) The peak of thermal emission will be at a shorter wavelength for the faster rotating star than for the slower rotating star.
D) There is no way to tell the stars apart spectroscopically, because their spectra will be identical. → A) The faster rotating star has wider spectral lines than the slower rotating star.