Which of the following conditions must be satisfied for laser action?
a. A ruby or similar crystalline material must be used.
b. A population inversion must occur.
c. The photons must be red.
d. A binary system must be used.
b
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A boulder following a straight-line path at constant velocity has
A) a net force acting upon it in the direction of motion. B) zero acceleration. C) no forces acting on it. D) none of the above
The Clausius form of the second law of thermodynamics states that
A. it is impossible to make heat flow from a colder to a hotter body B. heat naturally flows from a colder to a hotter body C. heat will not flow from a colder to a hotter body unless some other effect is involved
A nonconducting sphere contains positive charge distributed uniformly throughout its volume. Which statements about the potential due to this sphere are true? All potentials are measured relative to infinity
(There may be more than one correct choice.) A) The potential is highest at the center of the sphere. B) The potential at the center of the sphere is zero. C) The potential at the center of the sphere is the same as the potential at the surface. D) The potential at the surface is higher than the potential at the center. E) The potential at the center is the same as the potential at infinity.
Radiometric dating is based on
A) decay of uranium-238 to lead-206. B) sequence of rocks and the relative position of one layer to another. C) proportions of radioactive isotopes and their decay products. D) the half-life of radioactive atoms.