Question

How do you find the focal length of a convex lens experimentally ?​

Answer 1

Answer:

It can be found by obtaining a sharp image of the Sun or a distant tree on a screen, say a plane wall, or a sheet of paper placed on the other side of the lens and measuring the distance between the lens and the image with a scale. This distance is a rough estimate of the focal length, f of the convex lens.

Explanation:

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