A convex lens has a focal length of 25 cm. Calculate the distance of the object from the lens if the image is to be formed on the opposite side of the lens at a distance of 75 cm from the lens. What will be the nature of image ?

Given f = 25 cm, v = 75 cm, u =?

Using 1/v-1/u = 1/f

We have 1/u = 1/v-1/f = 1/75-1/25 = 1-3/75 = -2/75

Therefore u = -37.5

The image is real, inverted and magnified.