Quasar spectra often show the same hydrogen absorption line with several different redshifts. What do these lines represent?
A) clouds of gas at different distances between us and the quasar
B) different elements in the accretion disk around the quasar
C) different elements in the Earth's atmosphere
D) a single cloud of gas with clumps moving at different speeds
E) hydrogen gas orbiting the quasar's central black hole at high speed
A) clouds of gas at different distances between us and the quasar
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A. Kerning B. Primary C. Tracking D. Typography Reset Selection
Motional Emf: An electromagnetic flowmeter is useful when it is desirable not to interrupt the system in which the fluid is flowing (such as the blood in an artery during heart surgery). Such a device is illustrated in the figure. The conducting fluid moves with speed v in a tube of diameter d. Perpendicular to this tube is a magnetic field B. A voltage V is induced between opposite sides of the tube due to the motion of the conducting fluid in the magnetic field. For a certain case, B = 0.120 T, d = 1.2 cm, and the measured voltage is 10-3 = 2.88 mV. Determine the speed of the fluid. 
A. 2.0 m/s B. 11 m/s C. 0.075 m/s D. 1.1 m/s E. 750 m/s
In order of size from smallest to largest, the five terrestrial worlds are
A) Mercury, Venus, Earth, Moon, Mars. B) Mercury, Moon, Venus, Earth, Mars. C) Moon, Mercury, Venus, Earth, Mars. D) Moon, Mercury, Mars, Venus, Earth. E) Mercury, Moon, Mars, Earth, Venus.
A beam of laser light is
a. neither monochromatic nor coherent. b. monochromatic but not coherent. c. coherent but not monochromatic. d. both monochromatic and coherent.