Interstellar gas is composed mainly of
A) some hydrogen, but mainly carbon dioxide.
B) 10% hydrogen, 90% helium by numbers of atoms.
C) 90% hydrogen, 9% helium by weight.
D) ammonia, methane, and water vapor.
E) only hydrogen.
C
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An uncharged metal sphere is placed on an insulating puck on a frictionless table. While being held parallel to the table, a rod with a charge q is brought close to the sphere, but does not touch it. As the rod is brought in, the sphere
A. remains at rest. B. moves toward the rod. C. moves away from the rod. D. moves perpendicular to the velocity vector of the rod. E. moves upward off the puck.
What is the energy of a photon that has the same wavelength as a 11.4-eV electron? (h = 6.63 × 10^?34 J?s, me = 9.11 × 10^–31 kg, 1 eV = 1.6 × 10^–19 J)
a. 1140 eV b. 32 eV c. 103 eV d. 3420 eV e. 1030 eV
EM waves tend to be scattered the most by an object that is
A. conducting. B. about the same size as the wave. C. magnetic. D. reflective. E. a liquid.
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