JEE Main2017PhysicsRay OpticsActual
A diverging lens with magnitude of focal length 25 cm is placed at a distance of 15 cm from a converging lens of magnitude of focal length 20 cm . A beam of parallel light falls on the diverging lens. The final image formed is:
Options
- AReal and at a distance of 6   cm from the convergent lens
- BReal and at a distance of 40   cm from convergent lens
- CVirtual and at a distance of 40   cm from convergent lens
- DReal and at a distance of 40   cm from the divergent lens
Correct answer
B. Real and at a distance of 40   cm from convergent lens
Step-by-step solution
Diverging lens forms the image at its focus. The image formed by diverging lens is the object for converging lens. ∴ Distance of the object from converging lens is 40   cm i.e., object is at double focal point. ∴ Image forms at double focal point on the other side of the lens. 1 v - 1 4 = 1 f 1 v - 1 - 40 = 1 20 1 v + 1 40 = 1 20 1 v = 1 20 - 1 40 = 1 40 v = 40