to find the image distance for varying object distance in case of 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 image change ?

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Solution

1. (a) He should move the screen towards the lens to focus the object. This is because as the object move away from the screen,the image move towards the lens.
2. (b) The size of the image decreases as the object is moved away from the focus.

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1. (a) He should move the screen towards the lens to focus the object. This is because as the object move away from the screen,the image move towards the lens. 2. (b) The size of the image decreases as the object is moved away from the focus.

1. (a) He should move the screen towards the lens to focus the object. This is because as the object move away from the screen,the image move towards the lens.
2. (b) The size of the image decreases as the object is moved away from the focus.