Clear, student-friendly explanation of why the answer is correct
In myopia, light rays converge in front of the retina rather than on it. A concave (diverging) lens diverges incoming light rays so that the focal image forms accurately on the retina.
निकट दृष्टि दोष (मायोपिया) में वस्तु का प्रतिबिंब रेटिना के आगे बन जाता है। इसे रेटिना पर केंद्रित करने हेतु अवतल (Concave) लेंस का चश्मा प्रयुक्त होता है।
Dissection of why each option is correct or incorrect
| Option | Status | Critical Educational Reasoning |
|---|---|---|
| (A) Convex Lens (अभिसारी / उत्तल लें... | Incorrect | Incorrect. A convex (converging) lens is used to correct Hypermetropia (far-sightedness), where light rays focus behind the retina. |
| (B) Concave Lens (अपसारी / अवतल लेंस... | Correct | Correct. A concave (diverging) lens is prescribed for Myopia because it diverges incoming parallel light rays before they enter the eye, shifting the focal point back onto the retina. |
| (C) Bifocal Lens (द्विफोकसी लेंस) | Incorrect | Incorrect. Bifocal lenses (having both concave upper segment and convex lower segment) are used to correct Presbyopia, an age-related loss of accommodation of the ciliary muscles. |
| (D) More than one of the above / उपर... | Incorrect | Incorrect. Only a concave lens is required for simple myopia correction. |
| (E) None of the above / उपर्युक्त मे... | Incorrect | Incorrect. Option B is scientifically verified. |
Master the topic deeply rather than simply memorizing the answer
In a person with normal vision (emmetropia), light rays refract through the cornea and crystalline lens to form a sharp image directly upon the light-sensitive retina. In Myopia (short-sightedness), distant objects appear blurred because the eyeball is elongated along its antero-posterior axis, or the refractive power (curvature) of the cornea and crystalline lens is too great. Consequently, rays from distant objects converge to a focal point in front of the retina. A diverging (concave) lens with suitable negative focal length produces a virtual image at the person's far point, allowing parallel rays to focus accurately on the retina.
High-yield revision points frequently tested in BPSC TRE examinations
Avoid common traps and confusing options in this topic
Candidates often confuse the lens types for myopia versus hypermetropia. Quick mnemonic: M-C-H-C -> Myopia uses Concave lens; Hypermetropia uses Convex lens.
Authoritative books, official notifications, and standard reference materials
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