The optical shape of segmented mirrors is controlled by computer-driven thrusters under the mirrors in what is called
a. an achromatic lens.
b. active optics.
c. a Schmidt-Cassegrain design.
d. a Newtonian design.
e. interferometry.
b
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When the equation Ga + Br2 ? GaBr3 is balanced, the total of all the coefficients (both written and "understood") is
a. 4. b. 3. c. 6. d. 7.
Three identical point charges Q are placed at the vertices of an equilateral triangle (length of each side = 2.0 m). If Q = 60 ?C, what is the magnitude of the electrostatic force on any one of the charges?
a. 25 N b. 19 N c. 14 N d. 22 N e. 16 N
When water freezes, the surrounding air is
1) cooled, 2) warmed, 3) unchanged, and when ice melts, the surrounding air is 4) cooled. 5) warmed. 6) unchanged.
What should be the angle between the reflecting surfaces of two plane mirrors in order for every incident beam to be parallel to its reflected beam?
A) 0° B) 30° C) 45° D) 60° E) 90°