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Difficulty: MediumThin Lenses, Optical Instruments, and Defects of Vision

Match each visual defect or optical condition listed in Column A with its corresponding cause and corrective lens in Column B.

  • Myopia (Short-sightedness)Light rays from distant objects focus in front of the retina; corrected using a diverging (concave) lens.
  • Hypermetropia (Long-sightedness)Light rays from near objects focus behind the retina; corrected using a converging (convex) lens.
  • AstigmatismCornea or eye lens has uneven curvature in different planes; corrected using a cylindrical lens.
  • PresbyopiaLoss of elasticity of the crystalline lens and ciliary muscles due to aging; corrected using bifocal or converging lenses.

Answer

Myopia pairs with rays focusing in front of the retina (diverging lens correction); Hypermetropia pairs with rays focusing behind the retina (converging lens correction); Astigmatism pairs with uneven corneal curvature (cylindrical lens correction); Presbyopia pairs with age-related loss of accommodation (bifocal lens correction).
Each defect of vision is accurately matched to its optical cause and standard corrective device: Myopia uses diverging lenses to push the image focal plane onto the retina, Hypermetropia uses converging lenses to pull the image forward onto the retina, Astigmatism uses cylindrical lenses for non-spherical corneal curves, and Presbyopia uses bifocal/converging lenses to correct age-related accommodation loss.

Step-by-Step Solution

1
Analyze Myopia
Myopia causes distant rays to focus before reaching the retina because the eye lens is overly converging or the eye focal length is too short; a diverging (concave) lens spreads rays to push the focal point back onto the retina.
Identify optical cause and lens remedy for short-sightedness.
2
Analyze Hypermetropia
Hypermetropia causes near rays to focus behind the retina; a converging (convex) lens bends incoming light rays inwards to bring the focal point onto the retina.
Identify optical cause and lens remedy for long-sightedness.
3
Analyze Astigmatism
Astigmatism arises from non-uniform curvature of the refracting surfaces, requiring a cylindrical lens with differential curvature along different planes.
Identify refractive error causing multiple focal planes.
4
Analyze Presbyopia
Presbyopia is due to age-induced stiffening of the eye lens and loss of ciliary accommodation power, which is managed using bifocal or converging lenses.
Distinguish physiological aging effects on focal accommodation.

Key Concept

Defects of Vision and Corrective Lenses
Estimated Time:1m 30s
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Topics

Thin Lenses, Optical Instruments, and Defects of Vision

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