The image obtained with a convex lens is erect and its length is `4` times the length of the object. If the focal length of lens is `20 cm`, calculate the object and image distances.

The image obtained with a convex lens is erect and its length is `4` t

1.	The image obtained with a convex lens is erect and its length is `4` times the length of the object. If the focal length of lens is `20 cm`, calculate the object and image distances.
Answer» Here, `f = 20 cm, m = + 4`, for erect image. From `m = (f)/(u + f)` `4 = (20)/(u + 20) , u = -15 cm` From `m = (f - v)/(f)` `4 = (20 - v)/(20) , v = -60 cm`.

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The image obtained with a convex lens is erect and its length is `4` times the length of the object. If the focal length of lens is `20 cm`, calculate the object and image distances.

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