5 Written questions
5 Matching questions
- Lines of a particular element appear at the same wavelength in both emission and absorption line spectra
- X rays, because they have more energy, travel through space faster than visible light.
- From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.9 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.
- Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?
A) The star is moving away from us.
B) The star is getting hotter.
C) The star is moving toward us.
D) The star is getting colder.
- Suppose you have a chunk of water ice. Describe what happens to it, in terms of phases, as you raise the temperature to millions of degrees.
- a False
- b A) The star is moving toward us.
- c True
- d The ice melts into liquid, then evaporates into gas. At higher temperatures, the water molecules dissociate atoms. At very high temperatures, the atoms are ionized.
- e C) The star is moving toward us.
5 Multiple choice questions
- 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.
- 1) B
- A) Electrons orbit the nucleus rather like planets orbiting the Sun.
- D) have different sets of spectral lines.
5 True/False questions
Which of the following objects is not a close approximation of a thermal emitter?
A) hot, thin gas
B) a star
C) a filament in a light bulb D) you
E) a planet → A) hot, thin gas
The atomic nuclei of the same element always have the same number of protons. → False
Without telescopes or other aid, we can look up and see the Moon in the night sky because it
A) emits visible light.
B) emits thermal radiation.
C) reflects infrared light.
D) reflects visible light.
E) glows through radioactive decay. → D) reflects visible light.
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.
Any object moving relative to Earth will have a Doppler shift. → False