Lenses can focus light and make images in a very similar way to mirrors.
Both concave and convex lenses are used in a variety of optical instruments that will be studied in the next lecture. As in the case of mirrors, there are three prototypical cases. Hence the magnification M is positive, so the virtual image is not inverted. The third prototypical case is the peep-hole lens , a diverging lens used to make a virtual image that is smaller than the object. A converging lens will focus light from a distant source to the point called the focal point.