AIPMT PRELIMS2012Physics-Optics
AIPMT PRELIMS 2012 Physics Mirror and Lens Combination MCQ Question
Type: MCQ-conceptual-Medium-Class 12
A concave mirror of focal length f₁ is placed at a distance of d from a convex lens of focal length f₂. A beam of light coming from infinity and falling on this convex lens-concave mirror combination returns to infinity. The distance ‘d’ must equal
A
−2f₁ + f₂
B
f₁ + f₂
C
−f₁ + f₂
D
2f₁ + f₂
Correct Answer
Option D
Detailed Explanation
For the light to return to infinity, the effective focal length of the system must be zero. This condition is satisfied when d = 2f₁ + f₂.
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