Most Important Selected Qs for JEE AdvancedPhysicsRay Optics
The final image I of the object O shown in the figure is formed at point 20 cm below a thin equal-concave lens, which is at a depth of 65 cm from principal axis. From the given geometry, calculate the radius of curvature in cm of lens kept at "A".
Correct answer
60
Step-by-step solution
Image formation due to convex lens 1 V - 1 -36 = 1 30 v= 30 36 6 =180 ~cm This image will act like a virtual object for mirror and after reflection from mirror its image (shown by I2) will be formed at 80 cm below optical axis of convex lens. For concave lens, this image will be object at a position of 15 cm below the lens. For final image formed by concave lens. 1 20 - 1 15 = 1 f 1 f =- 5 300 Also, 1 f =( -1) (- 1 R - 1 R ) Or - 5 300 = ( 3 2 -1 ) ( -2 R ) R= 300 5 Ans. Radius of curvature =60 ~cm