Question

28. Two plano-concave lenses of glass of refractive
index 1.5 have radil of curvature of 20 cm and 30
cm. They are placed in contact with curved
surfaces towards each other and space between
them is filled by liquid
). Focal length of
lens system is
(1) -36 cm
(2) 72 cm
(4) 36 cm.
(3) -72 cm​

Answer 1

Please refer to The image

Answer - Option (D) -72

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