NTA Abhyas JEE Main2020PhysicsRay OpticsPractice
A real image is formed by a convex lens. If we put a concave lens in contact with it, the combination again forms a real image. The new image
Options
- Ais closer to the lens system
- Bis farther from the lens system
- Cis at the original position
- Dmay be anywhere depending on the focal length of the concave lens.
Correct answer
B. is farther from the lens system
Step-by-step solution
When concave lens is put in contact with convex lens, real/image is formed i.e., equivalent lens is convex. The focal length of equivalent lens F is greater than focal length of convex lens. 1 v - 1 - u = 1 f ⇒ 1 v = 1 f - 1 u = u - f f u v = u f u - f = u u f - 1 As f increases, u f decreases u f - 1 also decreases Thus, v increases.