JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
A collimated beam of light of diameter 2 mm is propagating along x -axis. The beam is required to be expanded in a collimated beam of diameter 14 mm using a system of two convex lenses. If first lens has focal length 40 mm , then the focal length of second lens is _________ mm.
- A 140
- B 280
- C 80
- D 200
Answer & Solution
Correct Answer
(B) 280
Step-by-step Solution
Detailed explanation
\(\frac{40}{2}=\frac{f}{14}\) \(\Rightarrow f =280 mm\)
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