An optical system is located in air. Let be its optical axis, and are the front and rear focal points, and are the front and rear principal planes, and are the conjugate points. By means of plotting find: (a) the positions and (Fig. ); (b) the position of the point conjugate to the point S (Fig. (c) the positions , and (Fig. , where the path of the ray of light is shown before and after passing through the system).
