If we are optimistic in our assumptions about the development of life and intelligence, then the number of technological civilizations currently in the galaxy should equal the
A) average lifetime of a civilization.
B) number of stars in the galaxy's habitable zone.
C) average number of planets per star.
D) number of stars forming per year.
E) average number of planets that produce life.
A
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2.00 moles of an ideal gas is at a pressure of 1.50 atmospheres and a volume of 0.00100 m3. What is the total kinetic energy of the gas?
A. 175 J B. 228 J C. 267 J D. 303 J E. 367 J
Violet light with a wavelength of 430 nm falls on a sodium plate (W = 2.75 eV) and a potassium plate (W = 2.30 eV). Which of of the following statements is true?
A. Both plates emit electrons, but those emitted by the sodium plate have the larger kinetic energy. B. Both plates emit electrons, but those emitted by the potassium plate have the larger kinetic energy. C. Only the sodium plate emits electrons. D. Only the potassium plate emits electrons. E. Neither plate emits electrons.
How is the magnification, mo, of the objective lens in a microscope related to the focal length, fo, of the lens?
A. Amo= -1/fo B. mo= -fo/L C. mo= -L/fo D. mo= L - fo
A beam of electrons has
A) wave properties. B) particle properties. C) both of these D) neither of these