Ray Optics And Optical Instruments Ques 36
36. A convex lens and a concave lens, each having same focal length of $25 $ $cm$, are put in contact to form a combination of lenses. The power in diopters of the combination is
[2006]
(a) $50$
(b) infinite
(c) zero
(d) $25$
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Answer:
Correct Answer: 36.(c)
Solution:
- (c) From the formula,
$\frac{1}{f}=\frac{1}{f_1}+\frac{1}{f_2}=\frac{1}{25}-\frac{1}{25}=0$
Power of combination $=\frac{1}{f}=0$
BETA
