Mike is taking a photograph of his friend who is posing at a distance of ‘u’ m away from the camera. If the focal length of the convex lens in the camera is 50 mm and the distance of the real image formed is 60 mm, then calculate ‘u’.

A camera fitted with a lens of focal length 50 mm is being used to photograph a flower that is 5 cm in diameter. The flower is placed 20 cm in front of the camera lens. (a) At what distance from the film should the lens be adjusted to obtain a sharp image of the flower ? (b) What would be the diameter of the image of the flower on the film ? . (c) What is the nature of camera lens ?

A point object is placed at a distance of 15 cm from a convex lens. The image is formed on the other side at a distance of 30 cm from the lens. When a concave lens is placed in contact with the convex lens, the image shifts away further by 30 cm. Calculate the focal lengths of the two lenses.