To find the image distance for varying object distances in case of a convex lens of focal length 15cm, a student obtains on a screen a sharp image of a bright object by placing it at 20cm distance from the lens. After that he gradually moves the object away from the lens and each time focuses the image on the screen.
a) In which direction- towards or away from the lens does he move the screen to focus the object?
b) How does the size of the image change?

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Solution

Hi,

(a) He should move the screen towards the lens to focus to focus the object.
(b) As the distance of object from the lens increases, size of image will get reduced.

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Hi, (a) He should move the screen towards the lens to focus to focus the object. (b) As the distance of object from the lens increases, size of image will get reduced.

Hi,

(a) He should move the screen towards the lens to focus to focus the object.
(b) As the distance of object from the lens increases, size of image will get reduced.