Q23.An object is at a distance of 20 m from a convex lens of focal length 0.3 m. The lens forms an image of the object. If the object moves away from the lens at a speed of 5 m/s the speed and direction of the image will be (1) 2.26 × 10−3 m/s away from the lens (2) 0.92 × 10−3 m/s away from the lens (3) 3.22 × 10−3 m/s towards the lens (4) 1.16 × 10−3 m/s towards the lens
What This Question Tests
This question combines the lens formula with differential calculus to determine the speed and direction of the image formed by a convex lens when the object is moving.
Concepts Tested
Formulas Used
1/f = 1/v - 1/u
dv/dt = (v/u)^2 (du/dt)
📚 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.
9.8 — 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?
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
- Lens formula, speed of image
- Year
- 2019
- Shift
- 11 Jan Shift 1
- Q Number
- Q23
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 9: Ray Optics
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