Optics Question 634
A achromatic combination is made with a lens of focal length $ f $ and dispersive power $ \omega $ with a lens having dispersive power of $ 2\omega $ . The focal length of the second lens will be
[RPET 1997]
Options:
2 f
B) $ f/2 $
C) $ -f/2 $
D) ? 2 f
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Answer:
Correct Answer: D
Solution:
$ \omega /f=-2\omega /f’\Rightarrow f’=-2f $
BETA
