Question

The main idea of the passage is Nearsightedness and farsightedness produce contrasting vision problems, have opposite causes, and require different types of lenses. How does the detail in bold develop the main idea?

a) It addresses a common misunderstanding about the causes of farsightedness.

b) It contrasts the cause of farsightedness with that of nearsightedness.

c) It provides additional information about corrective lenses.

d) It explains the prevalence of nearsightedness and farsightedness in the population.

Answer 1

The detail in bold highlights the contrasting causes of nearsightedness and farsightedness, with the former often caused by an eye that is too long or a lens that is too strong, and the latter by insufficient lens power or an eye that is too short.

Step-by-step explanation:

The detail in bold contrasts the cause of farsightedness with that of nearsightedness (option b). Nearsightedness, or myopia, involves the eye overconverging nearly parallel rays from a distant object, with the rays intersecting in front of the retina. This condition is corrected with a diverging lens. Conversely, farsightedness, or hyperopia, occurs when the eye does not converge rays from a close object sufficiently, preventing the rays from meeting on the retina. This is corrected with a converging lens. Essentially, the causes for both conditions relate to the eye's convergence power relative to the eye's length, with nearsightedness often involving an eye that is too long or a lens that is too powerful. In contrast, farsightedness may be due to insufficient power in the lens or an eye that is too short.