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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Harlow Shapley concluded that the Sun was not in the center of the Milky Way Galaxy by
A) looking at the shape of the "milky band" across the sky. B) mapping the distribution of stars in the galaxy. C) mapping the distribution of globular clusters in the galaxy. D) mapping the distribution of gas clouds in the spiral arms. E) looking at other nearby spiral galaxies.
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.
Radioactive Decay: Rutherfordium-261 has a half-life of 1.08 min. What is the decay constant of rutherfordium-261 in terms of seconds?
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