A lightbulb is connected to a 120 V(rms), 60 Hz source. How many times per second does the current reverse directions?
A. 60
B. 130
C. 120
D. 30
D. 30
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Which of the following would decrease the magnification of a compound microscope?
a. Replacing the objective lens with one of larger diameter. b. Replacing the eyepiece lens with one of shorter focal length. c. Replacing the eyepiece lens with one of smaller diameter. d. Replacing the objective lens with one of longer focal length.
A ball is thrown horizontally from the top of a building 0.10 km high. The ball strikes the ground at a point 65 m horizontally away from and below the point of release. What is the speed of the ball just before it strikes the ground?
a. 43 m/s b. 47 m/s c. 39 m/s d. 36 m/s e. 14 m/s
In the critical universe now proposed, the ratio of matter/energy is about:
A) 50:50. B) 27:73. C) 75:25. D) 10:90. E) 95:5.
Two equal point charges are separated by a distance d. When the separation is reduced to d/4, what happens to the force between the charges?
A. it decreases by a factor of 4 B. it increases by a factor of 4 C. it increases by a factor of 8 D. it increases by a factor of 16 E. it increases by a factor of more than 16