Given figures show the arrangements of two lenses, The radii of curvature of all the curved surfaces are same. The ratio of the equivalent focal length of combinations $P,\ Q\ and\ R$ is [image:9_image1.emf]

Question

Dr. Abubacker · Accepted Answer

(a) In given images, $P,\ Q$ and $R$ lenses in contact for $P$ combination of lenses
$\frac{1}{F_{P}} = \frac{1}{f} + \frac{1}{f} = \frac{2}{f}$
$F_{P} = \frac{f}{2}$
Similarly for $Q$ and $R$ combination
$F_{Q} = \frac{f}{2}$
$F_{R} = \frac{f}{2}$
Then $P\ :Q\ :R = 1\ :1\ :1$

Q. Given figures show the arrangements of two lenses, The radii of curvature of all the curved surfaces are same. The ratio of the equivalent focal length of combinations $P,\ Q\ and\ R$ is

Explanation

Reviewed by Dr. Abubacker

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