CHAPTER 13 SPHERICAL MIRRORS Concave and convex mirrors behave very differently in how they reflect light (Fig. 13.2).
FIG. 13.2 The C Curve, a huge concave/convex stainless steel mirror by artist Anish Kapoor, shows how differently concave and convex mirrors reflect light
Concave mirrors
As with plane mirrors, we first need to list the terms and rules associated with concave mirrors. This makes sketching light paths easier.
Terms used in spherical mirror diagrams principal axis C F pole
FIG. 13.3 A concave mirror
• Centre of curvature, C: the theoretical centre of the sphere from which the mirror was formed • Principal axis: the line joining the optical centre of the mirror to C (this is a ‘normal’) • Pole: the point at which the principal axis intersects the mirror • Focal point, F: halfway between C and the pole • Angle of incidence, i: the angle between the incident ray and the principal axis • Angle of reflection, r: the angle between the reflected ray and the principal axis
