Where the object gives a same-size image with a convex lens

The same question, asked 3 times: 2023*, 2024*, 2026. Every wording below, oldest first.

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Question 1
2023
30 $(a) The image of an object formed by a lens is of same size but inverted. If the object distance is 30 cm, calculate (i) The distance between the object and its image. (ii) Focal length of the lens. (b) Draw a ray diagram to show the image formed in above case.$
Question 2
2024
12 $At what distance from a convex lens should an object be placed to get an image of the same size as that of the object on a screen ?$
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Question 3
2026
30 $A convex lens of focal length 15 cm, is forming a real image. If the size of image is same as the size of object, then position of object and position of image will be, respectively :$
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Question 1