Sending signals at optical wavelengths might be a viable alternative to radio wavelengths
A) only between civilizations around solar-type stars whose eyes have evolved to see such radiation
B) over relatively short distances where absorption by interstellar matter would not be a problem
C) as long as the light transmitted is a different color than the light given off by the parent star
D) over all distances as long as the intensity of the signal is strong enough
B
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Matter Waves: What is the de Broglie wavelength of a ball of mass 200 g moving at 30 m/s? (h = 6.626 × 10-34 J ? s)
A. 1.1 × 10-34 m B. 2.2 × 10-34 m C. 4.5 × 10-28 m D. 6.7 × 10-27 m
The Big Dipper is a(n)
a. cluster of galaxies. b. constellation. c. galaxy. d. asterism.
A solid object has a volume density ?0 at a temperature of 315 K. The coefficient of volume expansion for the material of which it is made is 7.00 × 10-5 K-1
What will be its density (in terms of ?0 at a temperature of 425 K, assuming that it does not melt and that its thermal properties do not change with temperature?
The formation of a galactic central bulge is believed to ____
a. be a slow steady process lasting billions of years b. start after the formation of spiral arms c. be a violent process which adds mass to the central black hole d. begin when the central black hole has reached mature size e. continue throughout the galaxy's life body