What is the moderator of a nuclear reactor?
a. The control rods that halt a chain reaction if it is out of control.
b. A substance that absorbs neutrons to keep the reaction in control.
c. The material that slows down the neutrons to induce more chain reactions.
d. The material that speeds up the neutrons to induce more chain reactions.
e. The name for the fissionable material itself (usually uranium).
c
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An ultraviolet light wave has a wavelength of 300 nm and speed of 1.96 × 10^8 m/s through a transparent medium. What is the frequency of this wave in the medium? (1 nm = 10?9 m and c = 3.00 × 10^8 m/s)
a. 1.00E+15 Hz b. 3.27E+14 Hz c. 6.53E+14 Hz d. 6.53E+5 Hz e. 1.28E+7 Hz
A Doppler red shift indicates
a. a shift toward higher frequencies. b. a shift toward shorter wavelengths. c. that a light source is approaching relative to the observer. d. none of these.
When the frequency of the source of a water wave increases, the speed of the waves traveling in the water increases
a. True b. False Indicate whether the statement is true or false
The "efficiency" of a light bulb is the ratio of the:
a. heat plus electricity produced to the electrical input b. voltage output of the bulb to the power input c. energy into the bulb to the energy out of the bulb d. light output to the electrical energy input