How do astronomers calculate a telescope's light collecting area (A)? (where r = radius of the telescope's mirror or lens)
A. A = ?r2
B. A = 2?r
C. A = 4/3 ?r3
D. A = 4?r2
Answer: A
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Galaxies with disks but no evident spiral arms are called
A) irregular galaxies B) lenticular galaxies C) barred spiral galaxies D) elliptical galaxies
Compared to Uranus, Neptune has a smaller diameter and more mass. What can we conclude from this comparison?
A. Uranus spins faster and therefore has a larger diameter. B. Neptune has higher average density than Uranus. C. Uranus has higher average density than Neptune. D. The statement of the question is incorrect. Uranus is larger and has more mass than Neptune.
Planck's constant is about 7 × 10-34, in metric units. Suppose that Planck's constant were larger than it is actually is. Which of the following would then occur?
A) Individual photons would have larger energies, making it easier to observe individual photons. B) Individual photons would have larger wavelengths, making it easier to observe individual photons. C) Individual photons would move faster, even though the overall wave speed of electromagnetic radiation would not change. D) Individual photons would have shorter wavelengths, making it harder to observe individual photons. E) Individual photons would have smaller energies, making it harder to observe individual photons.
On a winter day the temperature is 5 degrees Celsius and the humidity is 0.003 kilograms per cubic meter. (a) What is the relative humidity? (b) The air is brought into a building and heated to 20 degrees Celsius without changing the humidity. What is the relative humidity inside the building?