A population inversion is a circumstance within a laser system in which there are ______ atoms with their electrons in an upper excited state than in a specific preferred lower state
a. more b. fewer
c. the same amount d. ionized
a
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The highest frequency visible light is
a. violet. b. red. c. blue. d. green. e. yellow.
Inelastic Collisions: In an inelastic collision involving an isolated system, the final total momentum is
A. exactly the same as the initial momentum. B. more than the initial momentum. C. less than the initial momentum.
How does the hypothesis of inflation account for the existence of the "seeds" of density from which galaxies and other large structures formed?
A) Inflation would have caused random, microscopic quantum fluctuations to grow so large in size that they became the seeds of structure. B) Inflation predicts that gravity would have been very strong and thereby would have concentrated mass into seeds. C) Inflation tells us that the universe should have a "flat" overall geometry, and this led to the flat disks of galaxies. D) Inflation predicts that temperatures and densities should have become nearly equal throughout the universe.
Springs: A 3.0-kg brick rests on a perfectly smooth ramp inclined at 34° above the horizontal. The brick is kept from sliding down the plane by an ideal spring that is aligned with the surface and attached to a wall above the brick. The spring has a spring constant (force constant) of 120 N/m. By how much does the spring stretch with the brick attached?
A. 360 cm B. 240 cm C. 14 cm D. 24 cm E. 36 cm