One half of a convex lens of focal length 10cm is covered with black paper. Can such a lens produce an image of a complete object placed at a distance of 30cm from the lens ? Draw a ray diagram to justify your answer. A 4cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20cm. The distance of the distance of the object from the lens is 15cm. Find the nature, position and size of the image.