Galaxies seem to be made mostly of dark matter. One type of evidence for this comes from observations of
A) the redshift in the light from the explosions of distant supernovas.
B) the redshift in the light from the earliest galaxies in the universe.
C) Both of the above.
D) the speeds at which gas clouds orbit the centers of galaxies.
E) distant quasars.
D
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Quasars may come from mergers of black holes in early galaxies
Indicate whether the statement is true or false
When two identical waves arrive at the same place in phase, there is
a. constructive interference b. destructive interference c. diffraction d. a Doppler effect e. a shock wave
If the objective lens of a compound microscope is replaced with a lens of double the focal length while the eyepiece also has its focal length doubled, what will happen to the overall magnification of the microscope?
a. This will result in no change in the magnification. b. The magnification doubles. c. The magnification quadruples. d. The magnification decreases.
The lowest tone to resonate in a closed pipe of length L is 200 Hz. Which of the following frequencies will not resonate in that pipe?
A) 1000 Hz B) 400 Hz C) 200 Hz D) 600 Hz E) 1400 Hz