Myopia and Its Cure

Q. A person can see clearly objects only when they lie between $50cm$ and $400cm$ 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, $+2.25$ dioptre
2. Concave, $-0.25$ dioptre
3. Concave, $-0.2$ dioptre
4. Convex, $+0.15$ dioptre

Q.

A man who cannot see clearly beyond 5 m wants to see stars clearly. He should use a lens of focal length

[MP PET/PMT 1988; Pb. PET 2003]

1. - 100 m

2. + 5 m

3. - 5 m

4. Very large