d) Converging and diverging lenses may be used in glasses to correct problems with eyesight. The diagram shows three parallel rays of light incident on a diverging lens and the path of the rays after passing through the lens. The diagram is drawn to actual size. O Add to the diagram to measure / determine the focal length of the lens. Focal length = 1 / focal length (f) = 1 / object distance (u) - 1 / image distance (v)