COMEDK2025PhysicsRay OpticsActual
A beam of incident parallel light falls on a diverging lens of focal length 20 cm in magnitude. If a converging lens of focal length 15 cm in magnitude is placed at a distance of 10 cm to the right of the diverging lens on the other side, then, the final image formed is:
Options
- AVirtual and is at a distance of 40 cm to the right of the diverging lens.
- BReal and is at a distance of 40 cm to the right of the converging lens.
- CReal and is at a distance of 30 cm to the right of the converging lens.
- DVirtual and is at a distance of 30 cm to the right of the converging lens.
Correct answer
C. Real and is at a distance of 30 cm to the right of the converging lens.
Step-by-step solution
For the diverging lens, the focal length f₁ = -20 cm. Since the incident light is parallel, the rays appear to diverge from the focus of the diverging lens located at 20 cm to the left of the lens. The image formed by the first lens acts as the object for the second lens. The position of this virtual object for the second lens is 10 cm (distance between lenses) + 20 cm (focal length of first lens) = 30 cm to the left of the converging lens. Thus, u₂ = -30 cm. For the converging lens, the focal length f₂ = +15 cm. U