Q25.A convex lens of refractive index 1. 5 and focal length 18 cm in air is immersed in water. The change in focal length of the lens will be_____ cm. (Given refractive index of water = 43 )
What This Question Tests
This question requires applying the Lens Maker's formula to calculate the focal length of a convex lens in air and then in water, and subsequently determining the change in focal length.
Concepts Tested
Formulas Used
1/f = (μ_lens/μ_medium - 1) (1/R1 - 1/R2)
📚 NCERT Sections This Tests
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?
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?
9.4 — Figures 9.27(A) And (B) Show Refraction Of A Ray In Air Incident At 60°
Physics Class 12 · Chapter 9
9.4 Figures 9.27(a) and (b) show refraction of a ray in air incident at 60° with the normal to a glass-air and water-air interface, respectively. Predict the angle of refraction in glass when the angle of incidence in water is 45° with the normal to a water-glass interface [Fig. 9.27(c)]. FIGURE 9.27
📋 Question Details
- Chapter
- Ray Optics
- Topic
- Lens Maker's Formula
- Year
- 2023
- Shift
- 24 Jan Shift 2
- Q Number
- Q25
- Type
- Numerical
- NCERT Ref
- Class 12 Physics Ch 9: Ray Optics and Optical Instruments
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