''Short-sight'' in human eye can be corrected by using proper:

Question

''Short-sight'' in human eye can be corrected by using proper:

1. A. Convex Lens
2. B. Concave Lens (Correct answer)
3. C. Cylindrical Lens
4. D. Bifocal Lens

Correct Answer

Option B — Concave Lens

Detailed Solution & Explanation

The correct answer is Concave Lens.

Key Points

• Short-sightedness (myopia) is caused by the eyeball being too long, focusing images in front of the retina.
• It is corrected using a concave (diverging) lens that diverges light before it enters the eye.

Additional Information

• Myopia (short sight) focuses distant images in front of the retina, because the eyeball is too long or the lens too converging. A concave (diverging) lens corrects it.
• Hypermetropia (long sight) focuses behind the retina and is corrected with a convex (converging) lens.
• Presbyopia, the age-related loss of accommodation, needs bifocal lenses; astigmatism, from an irregular curvature, needs cylindrical lenses.
• Lens power is measured in dioptres, the reciprocal of focal length in metres — negative for concave, positive for convex.