Q15.An object is placed at the focus of concave lens having focal length f. What is the magnification and distance of the image from the optical centre of the lens? (1) 4 1 , f4 (2) 12 , f2 (3) Very high, ∞ (4) 1, ∞
What This Question Tests
This problem tests the ability to apply the lens formula and magnification formula for a concave lens when the object is placed at its focus.
Concepts Tested
Formulas Used
1/f = 1/v - 1/u
m = v/u
📚 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.
9.2 — 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.
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
- Year
- 2021
- Shift
- 31 Aug Shift 1
- Q Number
- Q15
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 9: Ray Optics and Optical Instruments
More from this Chapter
Q64.An astronomical telescope has a large aperture to (1) reduce spherical aberration (2) have high resolution (3) increase span of observation (4) have low dispersion
Q65.If two mirrors are kept at 60∘ to each other, then the number of images formed by them is (1) 5 (2) 6 (3) 7 (4) 8
Q66.Which of the following is used in optical fibres ? (1) total internal reflection (2) scattering (3) diffraction (4) refraction
Q65.To get three images of a single object, one should have two plane mirrors at an angle of (1) 60∘ (2) 90∘ (3) 120∘ (4) 30∘