In an x-ray machine, electrons are accelerated and then fired so that they are incident on a metal target. Which part of the process produces the characteristic x-ray spectra?
a. The incident electron loses energy.
b. The incident electron knocks an electron out of one of the metal atoms.
c. A vacancy in an energy level in a metal atom is filled.
d. The incident electron emits an x-ray.
c
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Conduction: An architect is interested in estimating the rate of heat loss, ?Q/?t, through a sheet of insulating material as a function of the thickness of the sheet. Assuming fixed temperatures on the two faces of the sheet and steady state heat flow, which one of the graphs shown in the figure best represents the rate of heat transfer as a function of the thickness of the insulating sheet? 
A. A B. B C. C D. D E. E
Suppose you live at latitude 20°S. Based on the given right ascensions and declinations, which of the following stars passes closest to your zenith on its daily path through your sky?
A) Sirius: RA = 6hr 45m, dec = -16°42' B) Canopus: RA = 6hr 24m, dec = -52°41' C) Alpha Centauri: RA = 14hr 40m, dec = -60°50' D) Arcturus: RA = 14hr 16m, dec = +19°11' E) Vega: RA = 18hr 37m, dec = +38°47'
The uncharged particle inside an atom is
a. the electron. b. the proton. c. the neutron. d. the nucleus. e. none of the above.
Lenz's Law: The wire in the figure carries a current I that is decreasing with time at a constant rate. The wire and the three loops are all in the same plane. What is true about the currents induced in each of the three loops shown?
A. No current is induced in any loop. B. The currents are counterclockwise in all three loops. C. The currents are clockwise in all three loops. D. Loop A has clockwise current, loop B has no induced current, and loop C has counterclockwise current. E. Loop A has counterclockwise current, loop B has no induced current, and loop C has clockwise current.