Q

A convex lens of power 5 D is in contact with a concave lens of power -3 D. What is the combination's focal length?

RRB Group-D 22/08/2022 / Shift-II 2022
✓ Answer: A 50 cm
P = 5 - 3 = 2 D, so f = 1/2 m = 50 cm.
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