A planetary nebula is visible due to ____
a. blackbody continuum radiation from the interstellar medium
b. line emission from the interstellar medium
c. scattering from dust grains ejected by a dying star
d. blackbody continuum radiation from a hot gas ejected by a dying star
e. line emission from ionized hydrogen gas ejected by a dying star
e
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Energy in Capacitors: An air-filled capacitor has a potential difference between the plates of 80 V. If the charge on each of the plates of the capacitor has magnitude 8.0 ?C, what is the electrical energy stored by this capacitor?
A. 640 µJ B. 320 µJ C. 50 nJ D. 60 nJ E. 30 pJ
A battery operating a large flashlight produces a current of 2 amperes in a light bulb that has a resistance of 4 ohms. The voltage of the battery is
a. 0.5 volts c. 8 volts b. 2 volts d. none of the above
A scale from which a rock is suspended reads 5 N when the rock is out of water and 3 N when the rock is submerged. Buoyant force on the rock is
A) 2 N. B) 3 N. C) 4 N. D) 5 N.
The actual matter density of the universe, accounting for all of the luminous matter and all of the dark matter known to exist in galaxies and clusters, is what fraction of the critical density?
A) 25 percent B) 10 percent C) 200 percent D) 1 percent E) 100 percent