Question

Two identical thin plano-convex glass lenses (refractive
index 1.5) each having radius of curvature of 20 cm are placed
with their convex surfaces in contact at the centre. The
intervening space is filled with oil of refractive index 1.7.
The focal length of the combination is [2015]
(a) –25 cm (b) –50 cm
(c) 50 cm (d) –20 cm

Answer 1

Answer:

-50cm

Explanation:-

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