When the microwave background radiation was emitted, about how big was the universe?
A) smaller than the head of a pin
B) 1/1,000,000 its current size
C) 1/100,000 its current size
D) 1/1,000 its currents size
E) 1/100 its current size
D
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In which of the following types of galaxies would you expect to find active star formation?
a. elliptical galaxies only b. elliptical and spiral galaxies c. spiral galaxies only d. elliptical and irregular galaxies e. spiral and irregular galaxies
Most active galactic nuclei are powered by:
A) supermassive black holes. B) a large number of supernovae. C) mergers of compact objects. D) black hole mergers. E) extra-terrestrial civilizations.
A long, straight wire (radius = 2.0 mm) carries a current of 2.0 A distributed uniformly over a cross section perpendicular to the axis of the wire. What is the magnitude of the magnetic field at a distance of 1.0 mm from the axis of the wire?
a. 0.40 mT b. 0.80 mT c. 0.10 mT d. 0.20 mT e. 0.75 mT
The expression(s) indicating the number of neutrons in a nucleus is
a. A b. N c. Z d. Z + N e. A – Z