You hold a converging lens in front of a sheet of paper so as to form a sharp image of a distant object or scene from a window. You can use a ruler to measure the focal length of the lens. What would be a likely focal length (estimate). With this focal length, what is the refractive power of the lens?
You hold the converging lens directly in front of your eye and move a small object into a position where you can see a sharp magnified image of it. About how far would the object be from the lens (estimate)?