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#lens

2 public questions tagged with this topic.

PHYSICS

A double convex lens of refractive index 1.55 has radii of curvature 30 cm and -30 cm . What is its focal length?

Given: A double convex lens of refractive index 1.55 has radii of curvature 30 cm and -30 cm . What is its focal length? These values define the system as per NCERT data. Formula: Lens maker’s formula: 1/f = (n - 1) ( 1/R_1 - 1/R_2 ). This is standard NCERT relation. Substitution & Calculation: n = 1.55, R_1 = 30 cm, R_2 = -30 cm . 1/f = (1.55 - 1) ( 1/30 - 1/-30 ) = 0.55 ( 1/30 + 1/30 ) = 0.55 × 2/30 = 1.1/30 . f = 30/1.1 approx 27.27 cm . Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Relevant Physics topic covering fundamental principles,

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Eye Lens Induction -ll

What is the function of δ-crystallin in the lens?

Delta-crystallin, first crystallin characterized in chick lens, is a major structural protein highly expressed in lens fiber cells providing transparency, high refractive index, and protective stability. Recruited as metabolic enzyme argininosuccinate lyase with gene sharing property, delta-crystallin accumulates at high concentration in fiber cytoplasm increasing protein density and minimizing light scattering while lacking organelles. It does not form retina, promote corneal differentiation, or inhibit Wnt signaling. L-Maf transcription factor directly activates delta-crystallin enhancer dow

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 12: Delta-crystallin structural role and transparency function.

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