Quantrex Academy · Free JEE Advanced PYQ solutions
JEE Advanced Physics Ray Optics 2023 JEE Advanced 2023 (Paper 1)

JEE Advanced Physics Question (2023) — Solution

Question

An optical arrangement consists of two concave mirrors M 1  and M 2 , and a convex lens L with a common principal axis, as shown in the figure. The focal length of L is 10   cm . The radii of curvature of M 1 and M 2 are 20   cm and 24   cm , respectively. The distance between L and M 2 is 20   cm . A point object S is placed at the mid-point between L and M 2 on the axis. When the distance between L and M 1 is  n 7   cm , one of the images coincides with S . The value of n is _____(Consider the case which gives minimum value).

Options

  1. A. A
  2. B. B
  3. C. C
  4. D. D

Answer

A. A

Step-by-step solution

For reflection from M 2 : Applying mirror formula, we get 1 v + 1 - 10 = 1 - 12 ⇒ 1 v = 1 10 - 1 12 ⇒ v = + 60   cm  (for I 1 ) For refraction from L : Applying lens equation, we get 1 v - 1 u = 1 f ⇒ 1 v - 1 - 80 = 1 10 ⇒ v = + 80 7  (for  I 2 ) This image should be at focus of M 1 ∴   20 2 + 80 7 = n 7 ⇒ n = 150 Also, If I 2  is formed at pole of M 1 then  n 7 = 80 7 ⇒ n = 80 And further if I 2  is formed at centre of curvature of M 1  then n 7 = 80 7 + 20 ∴   n = 220 So value of  n  can be either  80   or   150   or   220 .

Practice more on Quantrex App →

Related: Physics — Ray Optics · All PYQ Banks