B
Paragraph 2 describes the problems of refractors—they didn’t “focus light sharply,” and they produced “color distortions.”
Choice (B) hits on the first problem. (A) is an exaggeration—the passage doesn’t say that the refractors didn’t transmit
colored light at all. (C) describes a reflector problem. There’s no evidence for (D), and (E) is not presented in the passage as
a problem.
47.
J
Lines 20–21 describe why scientists moved on to experimenting with reflectors—there were too many problems with
refractors. Refractors produced distorted images (a major problem in a telescope), as correct choice (J) suggests. (F) is
wrong because refractors had been invented—it’s just that they didn’t work. Lack of magnifying power (G) is not mentioned
as a problem. (H) is nonsense, and silver-coating (K) wasn’t invented until later in 1851.
48.
D
The practice of constructing lenses from layers of different kinds of glass is described at the end of paragraph 2. Scientists
investigated this option in order to overcome the problem discussed earlier—color distortion. The focusing problem (E) was
remedied by changing the curvature of lenses (lines 16–19). Cracking (C) was a problem associated with refractors
(paragraph 3).
49.
H
Lines 2–3 indicate the advantages of building large telescopes; “generally, the larger a telescope is, the greater its magnifying
power.” You can infer from this that larger telescopes are produced in order to enlarge the focused image for easier viewing
—choice (H).
50.
