Q36.A convex lens made of glass (refractive index = 1.5 ) has focal length 24 cm in air. When it is totally immersed in water (refractive index = 1.33 ), its focal length changes to (1) 24 cm (2) 96 cm (3) 48 cm (4) 72 cm
What This Question Tests
The question tests the ability to apply the Lens Maker's formula to calculate the focal length of a lens when it is immersed in a medium different from air.
Concepts Tested
Formulas Used
1/f = (ฮผ_lens/ฮผ_medium - 1)(1/R1 - 1/R2)
๐ NCERT Sections This Tests
9.7 โ Double-Convex Lenses Are To Be Manufactured From A Glass Of
Physics Class 12 ยท 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?
9.3 โ A Tank Is Filled With Water To A Height Of 12.5 Cm. The Apparent
Physics Class 12 ยท 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?
9.19 โ A Screen Is Placed 90Cm From An Object. The Image Of The Object On
Physics Class 12 ยท 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.
๐ Question Details
- Chapter
- Ray Optics
- Topic
- Lens Maker's Formula and immersion
- Year
- 2025
- Shift
- 29 Jan Shift 2
- Q Number
- Q36
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 9: Ray Optics and Optical Instruments
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