Q29.The distance between object and its 3 times magnified virtual image as produced by a convex lens is 20 cm . The focal length of the lens used is ________ cm .
What This Question Tests
This question involves using the lens formula and magnification formula for a convex lens to determine its focal length given the magnification of a virtual image and the distance between the object and image.
Concepts Tested
Formulas Used
1/f = 1/v - 1/u
m = v/u
|u - v| = distance between object and image
📚 NCERT Sections This Tests
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.
9.7 — 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?
9.8 — A Beam Of Light Converges At A Point P. Now A Lens Is Placed In The
Physics Class 12 · Chapter 9
9.8 A beam of light converges at a point P. Now a lens is placed in the path of the convergent beam 12cm from P. At what point does the beam converge if the lens is (a) a convex lens of focal length 20cm, and (b) a concave lens of focal length 16cm?
📋 Question Details
- Chapter
- Ray Optics
- Topic
- Lenses and Magnification
- Year
- 2024
- Shift
- 01 Feb Shift 1
- Q Number
- Q29
- Type
- Numerical
- NCERT Ref
- Class 12 Physics Ch 9: Ray Optics and Optical Instruments
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