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At which position will you keep an object in front of a convex lens so as to get a real image of the same size as the object? Draw a figure.

Question 3.

At which position will you keep an object in front of a convex lens so as to get a real image of the same size as the object? Draw a figure.


Answer:

In case of convex lens when the object is at “2F1”(twice of focal length), a real, inverted image of the same size is formed at “2F2

Explanation:


When the object is placed at the center of curvature of a lens then a ray of light AO which is parallel to the principal axis after refraction pass through the focus F along the direction OF. While the other ray AC pass through the optical center C and goes straight without any deviation. These two refracted light rays intersect each other at point A’, on the other side of the lens at the center of curvature 2F. so, the image A’B’ formed in this case is at the center of curvature, of the same size as the object, real and inverted.