In the symbol for the Hubble type of a galaxy, SBc, the "B" denotes
A. the presence of a bar
B. a large bulge component
C. loosely wound spiral arms
D. the presence of a ring
E. tightly wound spiral arms
Ans: A. the presence of a bar
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Planetary transits of exoplanets are rare because
A) most stars are too bright for us to detect a planetary transit. B) the Earth's atmosphere interferes with our observations of transits. C) our telescopes are not powerful enough to detect them. D) most extrasolar systems are not seen edge-on. E) most exoplanets are smaller than Pluto.
A quasar's spectrum is hugely redshifted. What does this large redshift tells us about the quasar?
A) the composition of the quasar B) the distance to the quasar C) the mass of the quasar's central, supermassive black hole D) the type of host galaxy in which the quasar resides
Fusion employs the lightest nuclei because
A. fusion produces a nucleus whose binding energy per nucleon is smaller than that of the two parent nuclei. B. they are more plentifully available. C. they are easier to completely ionize and thus cause their nuclei to coalesce. D. fusion produces a nucleus whose binding energy per nucleon is larger than that of the two parent nuclei.
A beam of neutrons (m = 939.6 MeV/c2) of momentum 12 keV is passed through a single slit of width 0.10 nm. As a result of this, the neutron beam acquires an uncertainty in the component of the momentum that is transverse to the beam direction. If the distance between the slit and a projection screen onto which the neutrons are projected is 1.5 m, what is the expected width of the neutron distribution on the projection screen in the transverse direction?
A. 155 cm B. 12 cm C. 25 cm D. 50 cm