An unfilled electron state in the valence band is called
A) a hole.
B) a positron.
C) an empty electron.
D) a conduction electron.
E) an empty positron.
A
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A. 0.0107 s-1 B. 0.0154 s-1 C. 1.87 s-1 D. 2.91 s-1 E. 0.344 s-1
Light of wavelength 500 nm illuminates a round 0.50-mm diameter hole. A screen is placed 6.3 m behind the slit. What is the diameter of the central bright area on the screen?
A) 15 mm B) 270 ?m C) 7.7 mm D) 3800 ?m
Harlow Shapley concluded that the Sun was not in the center of the Milky Way Galaxy by
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A three-dimensional image made using a laser is a(n)
a. emission spectrum. b. absorption spectrum. c. wave function. d. hologram. e. photoelectric effect.