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प्रश्न
The distance between an object and a convex lens is changing. It is noticed that the size of the image formed on a screen is decreasing. Is the object moving in a direction towards the lens or away from it?
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उत्तर
In the case of a convex lens, as the object moves away from it, the size of the image formed on a screen decreases.
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संबंधित प्रश्न
In a convex spherical mirror, reflection of light takes place at:
(a) a flat surface
(b) a bent-in surface
(c) a bulging-our surface
(d) an uneven surface
If the focal length of a spherical mirror is 12.5 cm, its radius of curvature will be:
(a) 25 cm
(b) 15 cm
(c) 20 cm
(d) 35 cm
An object is placed at a long distance in front of a convex mirror of radius of curvature 30 cm. State the position of its image.
Draw a labelled ray diagram to show the formation of image of an object by a convex mirror. Mark clearly the pole, focus and centre of curvature on the diagram.
What happens to the image when the object is moved away from the mirror gradually?
Two big mirrors A and B are fitted side by side on a wall. A man is standing at such a distance from the wall that he can see the erect image of his face in both the mirrors. When the man starts walking towards the mirrors, he find that the size of his face in mirror A goes on increasing but that in mirror B remains the same.
(a) mirror A is concave and mirror B is convex
(b) mirror A is plane and mirror B is concave
(c) mirror A is concave and mirror B is plane
(d) mirror A is convex and mirror B is concave
An object 1 cm tall is placed 30 cm in front of a convex mirror of focal length 20 cm. Find the size and position of the image formed by the convex mirror.
Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed:
- at 2F1,
- between F₁ and the optical centre O of the lens.
Which of the above two cases shows the use of a convex lens as a magnifying glass? Give reasons for your choice.
If the object is at infinity in front of a convex mirror the image is formed at infinity.
Which type of mirror is used in the following?
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