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QNEET-2019-Ph-808: NEET 2019 Physics - Class 12 NEET-2019-Ph-808 Solution: Two similar thin equi-convex lenses of focal length f each are…
Two similar thin equi-convex lenses of focal length f each are kept coaxially in contact with each other such that the focal length of the combination is . When the space between the two lenses is filled with glycerin (which has the same refractive index () as that of glass) then the equivalent focal length is . The ratio will be: 1:2 2:3 3:4 2:1
Multiple Choice Options
- A 1:02
- B 2:03
- C 3:04
- D 2:01
Step-by-Step Verified Solution
Equivalent focal length (in air) 1 F 1 = 1 f + 1 f = 2 f
When glycerin is filled inside, glycerin lens behaves
like a diverging lens of focal length (�f)
1 F 2 = 1 f + 1 f _ 1 f = 1 f
_ F 1 F 2 = 1 2