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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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°
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.