What's an isotope?
a. a radioactive material
b. an atom of an element with a different number of neutrons in the nucleus
c. an electrically charged atom
d. none of the above
B
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Consider a region of space where the electric field is uniform with magnitude 
, as shown below. What is the value of the specified potential difference in each case? (a) ?B - ?A? (b) ?C - ?B? (c) ?A - ?C?
A. 
B. 
C. 
D. 
E. 
F. 
T. zero
Wave Characteristics: A radio station broadcasts at a frequency of 80 MHz. How far from the transmitter will this signal travel in 67 ms? (c = 3.0 × 108 m/s)
A. 60 × 106 m B. 67 m C. 40 km D. 80 km E. 20 × 106 m
A 3 solar mass main sequence star is at the same distance as a 0.4 solar mass main sequence star. Which star appears brighter?
A. depends on the phase of the Moon B. the 0.4 solar mass main sequence star C. stars are approximately the same brightness D. the 3 solar mass main sequence star E. cannot tell with the information given
Which of the following is not consistent with recent observations of the cosmic microwave background by Planckt?
A) The universe is geometrically "flat" (in the four dimensions of spacetime). B) The matter density (both luminous and dark matter combined) in the universe is only about one-fourth of the critical density. C) Dark energy, whatever it is, represents the majority of the energy content of the universe. D) The universe is at least 20 billion years old.