Q17.A thin lens made of glass (refractive index = 1.5 ) of focal length f = 16cm is immersed in a liquid of refractive index 1.42 . If its focal length in liquid is fl , then the ratio fl/f is closest to the integer: (1) 1 (2) 9 (3) 5 (4) 17
What This Question Tests
This question tests the application of the lens maker's formula to determine the focal length of a lens first in air and then when immersed in a different liquid, requiring calculation of the ratio of focal lengths.
Concepts Tested
Formulas Used
1/f = (μ_lens/μ_medium - 1)(1/R₁ - 1/R₂)
📚 NCERT Sections This Tests
9.7 — Double-Convex Lenses Are To Be Manufactured From A Glass Of
Physics Class 12 · Chapter 9
9.7 Double-convex lenses are to be manufactured from a glass of refractive index 1.55, with both faces of the same radius of curvature. What is the radius of curvature required if the focal length is to be 20cm?
9.19 — A Screen Is Placed 90Cm From An Object. The Image Of The Object On
Physics Class 12 · Chapter 9
9.19 A screen is placed 90cm from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by 20cm. Determine the focal length of the lens.
9.3 — A Tank Is Filled With Water To A Height Of 12.5 Cm. The Apparent
Physics Class 12 · Chapter 9
9.3 A tank is filled with water to a height of 12.5 cm. The apparent depth of a needle lying at the bottom of the tank is measured by a microscope to be 9.4 cm. What is the refractive index of water? If water is replaced by a liquid of refractive index 1.63 up to the same height, by what distance would the microscope have to be moved to focus on the needle again?
📋 Question Details
- Chapter
- Ray Optics
- Topic
- Lens maker's formula
- Year
- 2020
- Shift
- 07 Jan Shift 2
- Q Number
- Q17
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 9: Ray Optics and Optical Instruments
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