The near point of a farsighted person's uncorrected eyes is 80 cm. What power contact lens should be used to move the near point to 25 cm from this person's eyes?
A) 2.8 diopters
B) -2.8 diopters
C) -4.0 diopters
D) -4.2 diopters
E) 4.2 diopters
A
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Which of these is a reason for using mirrors rather than lenses in telescopes?
A. Lenses can only be supported by their edges, making them sag in the middle (mirrors can be supported from behind). B. Most transparent materials focus light of different colors to different spots. C. Lenses are more expensive to make than mirrors. D. All of these choices are correct.
Which two bodies have geological features caused by liquid water?
a. Mercury and Venus b. Mercury and Earth c. Mercury and Earth's Moon d. Earth and Venus e. Earth and Mars
Kelli examines her new ruby ring with the jeweler's "loop". The ruby appears 7.0 times larger. If her near point is 35. cm, what is the focal length of the lens?
A) 36. mm B) 70. mm C) 67. mm D) 42. mm E) 58 mm
Which of the following extrasolar planets would be the most difficult to detect using the Doppler shift method?
A) a low mass planet far from its parent star B) a massive planet close to its parent star C) a low mass planet close to its parent star D) a massive planet far from its parent star