Hypermetropia (far-sightedness) and its correctionदीर्घ-दृष्टि दोष और उसका संशोधन

NCERT Fig 10.3 · interactive diagram

Parts and their functions

• Near point N of a hypermetropic eye (दीर्घ-दृष्टि दोषयुक्त नेत्र का निकट बिंदु N) — Farther than the normal near point N′ (25 cm). Reading material must be held far away.
• Image of a near object forms behind the retina (पास की वस्तु का प्रतिबिंब दृष्टिपटल के पीछे) — Cause: focal length of the eye lens too long, or the eyeball has become too small.
• Corrected eye (संशोधित नेत्र) — The converging lens makes rays from N′ appear to come from N, so the image falls on the retina.
• Convex lens of suitable power (उपयुक्त क्षमता का उत्तल लेंस) — Gives the extra converging power. e.g. near point 1 m → P = +3.0 D (NCERT Exercise 7).

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 10.3. Report a mistake