Images formed by a convex mirror
Unlike the concave mirror, which can produce either real or virtual images according to the position of the object, the convex mirror gives virtual images only. These are always erect and smaller than the object and are formed between P and F (see Fig. 22.12).
Fig. 22.13. Polishing the 17 tonne primary mirror of the British William erschel 4.2 metre telescope. The telescope is to be sited at the new International Observatory on La Palma in the Canary Islands. Using satellite communication links, the telescope will be controlled from a computer console at the Royal Greenwich Observatory at Cambridge in England. La Palma was chosen as the site of the new observatory for its exceptionally fine weather record. The whole project is a co-operative venture between the governments of Britain, Spain, Sweden, Denmark and Holland Convex mirrors are very convenient for use as car driving mirrors, since they always give an erect image and a wide field of view. Fig. 22.14 shows why a co nvex mirror has a wider field of view than a plane mirror of the same size.