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Choose the most appropriate option. Tw...

Choose the most appropriate option.
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 center. The intervening space is lled with oil of refractive index 1.7. The focal length of the combination is:

A

`-20 cm`

B

`-25 cm`

C

`-50 cm`

D

50 cm

Text Solution

Verified by Experts

The correct Answer is:
C
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  • Two identical thin planoconvex glass lenses (refractive index 1.5) each having radius of curvature of 20cm 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

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