Suppose the distance from the candle to the lens is 40 cm, and the distance from the lens to the screen is also 40 cm. What is the focal length of the lens?

The results of huy's eye exam show that he is nearsighted. which explanation should huy expect to hear? "you need convex lenses to shorten the distance that light takes to focus in your eyes." "you need concave lenses to shorten the distance that light takes to focus in your eyes." "you need convex lenses to lengthen the distance that light takes to focus in your eyes." "you need concave lenses to lengthen the distance that light takes to focus in your eyes."