Question Detail
Question
According to Example 2, if a myopic eye has a far point of 50 cm in front of the eye, what power of eyeglass lens is required to enable clear vision of an object at infinity?
Correct Answer
Option B is the correct answer.
Detailed Explanation
For an object at infinity (u = ∞), the corrective lens must form a virtual image at the eye's far point. The far point is 50 cm, so the desired image distance (v) is -50 cm (or -0.5 m). Using the lens formula 1/f = 1/u + 1/v: 1/f = 1/∞ + 1/(-0.5 m) = 0 - 2.0 m-1 = -2.0 m-1. Therefore, the power (1/f) is -2.0 diopters.
Hint
The corrective lens must form a virtual image of the distant object at the myopic eye's far point. Remember to use meters for focal length when calculating power and the correct sign for virtual images.