A photon emitted by an excited atom has an energy of 5 eV. What is its frequency?
1.21 × 10^15 Hz
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Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum?
A) The only way to decide is to make a graph of the intensity of the light at every wavelength, and then analyze the graph carefully. B) An emission line spectrum consists of a long bright line, while an absorption line spectrum consists of a long dark line. C) An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background. D) The emission line spectrum is produced by electrons jumping up in energy level, while the absorption line spectrum is produced by electrons jumping down in energy level.
The more its central black hole was fed, the more likely the galaxy was to show up as a quasar
Indicate whether the statement is true or false
A lawn mower has a 6-horsepower engine (1 HP = 750 W). If the engine has an efficiency of 20%, and the throttle is such that the engine cycles 10 times a second, the heat that is expelled in one cycle is
a. 1 800 J b. 2 000 J c. 2 200 J d. 2 400 J e. 2 250 J
What does a breeder reactor do?
a. Produces plutonium from uranium and thereby creates more nuclear fuel than it uses. b. Creates independent chain reactions that then separate from their parents and become new energy sources. c. Uses controlled rates of reaction to conserve nuclear fuel. d. Creates its own neutron bombardment beam out of the neutrons that escape from the uranium as it decays. e. Creates its own control rods out of the lead resulting from uranium decay.