The electrons in a cloud of hydrogen gas are making the transitionfrom excited states tothe ground state. What does the spectrum of this cloud of gas lookalike?
a) It will be completely black at all wavelengths.
b) It will be bright at every wavelength, giving off some radio waves, some visible light,and X-rays.
c) It will consist of a few bright emission lines at very specific wavelengths.
d) It will be bright at most colors, but with some dark absorption linesat very specific wavelengths.
e) It will be identical to the spectrum of the Sun.
Ans: c) It will consist of a few bright emission lines at very specific wavelengths.
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If each nuclear fission reaction in a nuclear power plant releases 
what quantity of Uranium-235 is used to produce the same amount of energy relased in burning a gallon of gasoline?
A. 28g B. 0.28g C. 2.8g D. 0.0028g
A long hollow cylindrical conductor (inner radius = 2.0 mm, outer radius = 4.0 mm) carries a current of 24 A distributed uniformly across its cross section. A long wire which is coaxial with the cylinder carries an equal current in the opposite direction. What is the magnitude of the magnetic field 3.0 mm from the axis?
A. 0.82 mT B. 0.93 mT C. 0.70 mT D. 0.58 mT E. 0.40 mT
The "surface" of a black hole is known as the ______________
Fill in the blank(s) with correct word
A sound source radiates sound uniformly in all directions. The intensity of the sound at a distance of 100 m is 
The power of the sound source is
A. 12.6 W. B. 16.2 W. C. 20.4 W. D. 24.5 W. E. 30.6 W.