Optics 3 Question 31
31. A convex lens $A$ of focal length $20 cm$ and a concave lens $B$ of focal length $5 cm$ are kept along the same axis with a distance $d$ between them. If a parallel beam of light falling on $A$ leaves $B$ as parallel beam, then $d$ is equal to …….. cm.
(1985, 2M)
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Answer:
Correct Answer: 31. 15
Solution:
- At $I _1$, second focus of convex lens should coincide the first focus of concave lens.
