Based on the observed amount of deuterium in the universe, we can conclude that
A) neutrons outnumber protons 7 to 1 in the universe.
B) most of the deuterium that was created during the era of nucleosynthesis has since been destroyed.
C) we live in a critical-density universe.
D) the density of ordinary (baryonic) matter is about 5 percent of the critical density.
E) ordinary (baryonic) matter makes 75 percent of the mass of the universe.
D
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The image formed by a concave mirror when the object distance is greater than the focal length is always
A. at a distance greater than the focal length. B. real. C. right side up. D. virtual.
A galvanometer calibrated to read potential difference is
A) an ammeter. B) a voltmeter. C) an ohm meter. D) none of the above
Two very small plastic balls of equal mass are released from rest. One of them carries +10 µC of excess charge and the other one carries +1µC of charge. No other charges or fields are present
Which of the following statements are true about them as they move away from each other? (There may be more than one correct choice.) A) The acceleration of the 10-µC ball is 10 times that of the 1-µC ball. B) The acceleration of the 1-µC ball is 10 times that of the 10-µC ball. C) The balls always have accelerations of equal magnitude. D) The speed of the balls keeps increasing. E) The acceleration of the balls keeps increasing.
A monochromatic (single frequency, single wavelength) light ray in air (n = 1) enters a glass prism (n = 1.5). In the glass prism
A. both the frequency and the wavelength are the same as in air B. the frequency is the same, but the wavelength is greater than in air. C. the frequency is the same, but the wavelength is smaller than in air. D. the wavelength is the same, but the frequency is greater than in air. E. the wavelength is the same, but the frequency is smaller than in air.