A thin convex lens of focal length $10\ cm$ is placed in contact with a concave lens of same material and of same focal length. The focal length of combination will be

Question

Dr. Abubacker · Accepted Answer

(b) $f = \frac{f_{1}f_{2}}{f_{1} + f_{2}} = \frac{10( - 10)}{10 + ( - 10)} = \frac{- 100}{10 - 10} = \infty$

Q. A thin convex lens of focal length $10\ cm$ is placed in contact with a concave lens of same material and of same focal length. The focal length of combination will be

Explanation

Reviewed by Dr. Abubacker

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