Q

A converging lens of focal length 50 cm is in contact with a diverging lens of focal length 20 cm. What is their combined power?

RRB Group-D 01/09/2022 / Shift-I 2022
✓ Answer: C +3 D
Source key C is retained, but the signs are reversed in the source calculation. Correctly, P = 1/0.5 + 1/(-0.2) = 2 - 5 = -3 D, which is option D.
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