The wavelength of a ruby laser is 694.3 nm. What is the energy difference between the two energy states involved in laser action? (c = 2.9979 × 108 m/s, h = 6.626 × 10-34 J ? s, 1 eV = 1.6022 × 10-19 J)
A) 1.537 eV
B) 1.646 eV
C) 1.786 eV
D) 1.812 eV
E) 3.572 eV
Answer: C
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Ocean tides are waves that have a period of 12 hours, an amplitude (in some places) of 1.50 m, and a speed of 750 km/hr. What is the distance between adjacent crests of these waves?
A) 9000 km B) 32,400 km C) 9000 m D) 32,400 m E) 2500 m
An umbrella tends to move upwards on a windy day principally because
A) trapped air under the umbrella, warms, and rises. B) buoyancy increases with increasing wind speed. C) air pressure is reduced over the curved top surface. D) all of the above
The thermal pressure in an object increases when the temperature increases, but the degeneracy pressure does not
Indicate whether the statement is true or false
Why didn't elements heavier than helium form in the first minutes of creation?
A) When He-4 was formed, the expansion cooled the cosmos below 100 million K. B) The first generation of stars used them up too quickly to observe them. C) The electrons slowed down enough to be captured into orbits by protons. D) There was not enough matter in the universe at that time. E) Only Type I supernovae can produce iron and heavier elements.