Among these choices, which is the first thing that happens in thehistory of the universe?
a) formation of nuclei of helium
b) binding of electrons to nuclei
c) first stars form
d) universe becomes transparent
e) first supernova explosions occur
Ans: a) formation of nuclei of helium
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Current: When a current flows through an ionic liquid such as salty water, the moving charges are
A. only protons. B. only electrons. C. only negative ions. D. only positive ions. E. both positive and negative ions.
Acceleration due to gravity is 9.8 m/s2 on the surface of Earth, and at orbits 200 miles above the surface of Earth, where the space shuttle orbits, the acceleration is
A. less than 9.8 m/s2. B. greater than 9.8 m/s2. C. exactly 9.8 m/s2-same as on the surface of Earth. D. undetermined, because it depends on the mass of the spacecraft or satellite.
Two narrow slits are 0.0280 mm apart. When a laser shines on them, bright fringes form on a screen that is a meter away. These fringes are 6.06 cm apart. What is the separation between the second-order bright fringe and the central fringe?
a. 1.70 cm b. 12.1 cm c. 12.0 cm d. 36.8 cm e. 6.34 cm
What is the direction of the neutral atom’s electric field at the location of the charged particle?
A. A B. B C. C D. D E. Zero F. Other G. AA H. BB I. CC J. DD