A person can see objects clearly only when they lie between 50 cm and 400 cm from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use, will be:
1. | convex, +2.25 D | 2. | concave, −0.25 D |
3. | concave, −0.2 D | 4. | convex, +0.5 D |
The near point of a hypermetropic person is 75 cm from the eye. What is the power of the lens required to enable the person to read clearly a book held at 25 cm from the eye?
1. +2.67 D
2. −1.25 D
3. −2.67 D
4. +1.25 D