Two lenses of power –15D and +5D are in contact with each other.
Two lenses of power –15D and +5D are in contact with each other. The focal length of the combination is
(a) + 10cm
(b) –20cm
(c) –10cm
(d) + 20cm
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1 Answers
(c) Power of combination = P1 + P2
= – 15D + 5D = – 10D.
Focal length of combination F = 1/P = 1/-10D
= -0.1m = -10cm
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Answered