(a) With the aid of ray diagrams, explain total internal reflection.

(b) Describe, with the aid of a labelled diagram, the essential features of an astronomical telescope in normal adjustment.

(c) A converging lens forms a real image of a real object. If the magnification is 2 and the distance between the image and the object is 90.0 cm, determine the

(i) focal length of the lens;

(ii) object distance for which the image would be the same size as the object.