STANDARD Physics Mirror and Lens Combination MCQ Question
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
f₁ + f₂
−f₁ + f₂
2f₁ + f₂
−2f₁ + f₂
Correct Answer
Detailed Explanation
For the light to return to infinity, the system must act as a plane mirror. This condition is satisfied when the distance d equals 2f₁ + f₂, ensuring that the light retraces its path.
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