NEET2026PhysicsChapterActual
A point object is placed at a distance of 30 cm from a convex lens of focal length 20 cm . A convex mirror of radius of curvature 120 cm is placed co-axially at a distance of 40 cm from the lens on the other side. The final image formed by the system would be at a distance of : (Assume paraxial rays and the reflecting surface of the mirror faces the lens)
Options
- A20 cm from the lens, it would be a virtual image.
- B20 cm from the lens, it would be a real image.
- C80 cm from the lens, it would be a virtual image.
- D30 cm from the convex mirror, it would be a real image.
Correct answer
A. 20 cm from the lens, it would be a virtual image.
Step-by-step solution
First refraction through the convex lens. For the convex lens, the object distance u₁ = -30 cm and focal length f₁ = +20 cm . Using the lens formula: 1 v₁ - 1 u₁ = 1 f₁ 1 v₁ - 1 -30 = 1 20 1 v₁ = 1 20 - 1 30 = 3 - 2 60 = 1 60 v₁ = +60 cm The first image I₁ is formed 60 cm to the right of the lens. Reflection from the convex mirror. The convex mirror is placed 40 cm to the right of the lens. The image I₁ acts as a virtual object for the mirror. Object distance for the mirror, u₂ = +(60 - 40) = +20 cm . Focal length