Learning objectives By the end of this chapter, you should be able to:
recognise the differences between concave and convex mirrors and give uses of each
sketch and explain the terms used in an optics diagram for mirrors
draw the formation of images in each type of mirror
Introduction
convex mirror
P
concave mirror
C hollow sphere
FIG. 13.1 A spherical mirror is a curved mirror that is part of a theoretical sphere
NOTE
Imagine you are looking into a ‘cave’ (concave, so the curve goes in) to decide which mirror is which.
P
You will have already studied the basics of light and reflection, but in order to fully appreciate the nature of optics we need
to break the section down into the two main optical forms: spherical mirrors and lenses. In this chapter, we look at spherical mirrors, their uses and the how to geometrically predict their image formations.
Imagine a mirror in the shape of a hollow sphere (Fig. 13.1). If you cut a section out of the sphere, you will have a spherical mirror.
There are two main types of spherical mirror, concave and convex, and which one you have depends on whether the reflective surface is on the inside or the outside of the theoretical sphere.
• Concave mirrors have their reflective surface on the inside of the theoretical sphere.
• Convex mirrors have their reflective surface on the outside of the theoretical sphere.
know where images appear in mirrors depending on object position
use the general optics formulae to calculate distances.
