Why has star formation ceased in the galactic halo?
A) The halo has no gas at all.
B) There are no white dwarf binaries to trigger star formation via their supernovae.
C) All the halo gas consists of elements with more protons than helium.
D) All of the galaxy's cool gas settled to the galactic plane long ago.
D
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Intensity: The intensity of the waves from a point source at a distance d from the source is I. What is the intensity at a distance 2d from the source?
A. 4I
B. 2I
C. I/2
D. I/4
E. I/
In a two-slit experiment, if the wavelength of the incident light increases, the bright and dark lines in the interference pattern
A. are unchanged. B. spread out. C. move closer together. D. disappear.
4.4 × 10^6 divided by 8.8 × 10^10 is equal to
a. 5.0 × 10^?5. b. 5.0 × 10^?4. c. 5.0 × 10^4. d. 3.9 × 10^17. e. 3.9 × 10^16.
Planetary orbits are
a. parabolas c. circles b. ellipses d. none of the above.