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प्रश्न
Where must a point source of light be placed in front of a convex lens so as to obtain a parallel beam of light?
उत्तर
At focus:
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संबंधित प्रश्न
Where should an object be placed so that a real and inverted image of the same size as the object is obtained using a convex lens?
Draw a labelled ray diagram to show how a ray of light is refracted when it passes:
from air into an optically denser medium.
Where should an object be placed in front of a convex lens so as to obtain its real, inverted and magnified image?
What is a lens?
Draw a ray diagram to show the formation of a real magnified image by a convex lens. (In your sketch the position of object and image with respect to the principal focus of lens should be shown clearly).
An object 2 cm tall is placed on the axis of a convex lens of focal length 5 cm at a distance of 10 m from the optical centre of the lens. Find the nature, position and size of the image formed. Which case of image formation by convex lenses is illustrated by this example?
If the object is moved to a point only 3 cm away from the lens, what is the new position, height and nature of the image?
What kind of lens can form:
an inverted diminished image?
A teacher sets up the stand carrying a convex lens of focal length 15 cm at 42.7 cm mark on the optical bench. He asks four students A, B, C and D to suggest the position of screen on the optical bench so that a distinct image of a distant tree is obtained almost immediately on it. The positions suggested by the students were as
A. 12.7 cm
B. 29.7 cm
C. 57.7 cm
D. 72.7 cm
The correct position of the screen was suggested by
(a) A
(b) B
(c) C
(d) D
A student focussed the image of a distant object using a device ‘X’ on a white screen ‘S’ as shown in the figure. If the distance of the screen from the device is 40 cm, select the correct statement about the device.
(A) The device X is a convex lens of focal length 20 cm.
(B) The device X is a concave mirror of focal length 40 cm.
(C) The device X is a convex mirror of radius of curvature 40 cm.
(D) The device X is a convex lens of focal length 40 cm.
