Doppler effect, redshift and the Hubble constant Quiz
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5 questions, one answer each
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1. A galaxy has a redshift of 0.020. What is its recession speed?
- A. 6.0 × 10⁶ m s⁻¹
- B. 6.0 × 10⁷ m s⁻¹
- C. 1.5 × 10¹⁰ m s⁻¹
- D. 2.0 × 10⁻² m s⁻¹
2. Light from a galaxy has a longer wavelength than the same light measured in the laboratory. What does this show?
- A. The galaxy is moving towards us
- B. The galaxy is stationary
- C. The galaxy is moving away from us
- D. The galaxy is very hot
3. What does Hubble's law say about the recession speed of a galaxy?
- A. It is proportional to its distance
- B. It is inversely proportional to its distance
- C. It is the same for all galaxies
- D. It is proportional to its luminosity
4. A larger value of the Hubble constant would give
- A. an older universe
- B. a younger universe
- C. no change in the age
- D. a universe of infinite age
5. Why is the fate of the universe uncertain?
- A. The speed of light is not known
- B. Redshift cannot be measured
- C. The amount of dark matter, and so the density of matter, is uncertain
- D. Galaxies are not moving