Q29.The distance between object and its two times magnified real image as produced by a convex lens is 45 cm. The focal length of the lens used is ________ cm .
What This Question Tests
This question tests the application of the lens formula and magnification formula for a convex lens to find its focal length, given the distance between object and its magnified real image.
Concepts Tested
Formulas Used
1/f = 1/v - 1/u
m = v/u
m = -v/u (Cartesian Sign Convention)
📚 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?
9.2 — A 4.5 Cm Needle Is Placed 12 Cm Away From A Convex Mirror Of Focal
Physics Class 12 · Chapter 9
9.2 A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification. Describe what happens as the needle is moved farther from the mirror.
📋 Question Details
- Chapter
- Ray Optics
- Topic
- Lenses
- Year
- 2024
- Shift
- 30 Jan Shift 1
- Q Number
- Q29
- Type
- Numerical
- NCERT Ref
- Class 12 Physics Ch 9: Ray Optics and Optical Instruments
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