Two lenses of power +3 D and −1 D are kept in contact. The combination behaves as a
A. concave lens of focal length 50 cm
B. convex lens of focal length 25 cm
C. concave lens of focal length 2 m
D. convex lens of focal length 50 cm
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Answer: D. convex lens of focal length 50 cm
\(P = 3 + (-1) = +2\) D, so \(f = \frac{1}{2}\) m = 50 cm. Positive power means it acts as a convex lens.
Doubtly AI
· 24 Oct 2026
AI-verified · Oct 2026
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