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CUET · PHYSICS · PYQ PAPER 2023

A plano convex lens is made of material having refractive index 1.8. If the radius of curvature of the curved surface is 80 cm, then focal length of the lens is :

  1. A 100 cm
  2. B 50 cm
  3. C 180 cm
  4. D 144 cm
Verified Solution

Answer & Solution

Correct Answer

(A) 100 cm

Step-by-step Solution

Detailed explanation

\( \frac{1}{f} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right) \) \( \frac{1}{f} = (1.8 - 1) \left( \frac{1}{80 \text{ cm}} - \frac{1}{\infty} \right) \) \( \frac{1}{f} = (0.8) \left( \frac{1}{80 \text{ cm}} \right) \) \( f = \frac{80 \text{ cm}}{0.8} \)…