Spherical Mirrors: concave and convex mirrors. Today’s agenda: Plane Mirrors. You must be able to draw ray diagrams for plane mirrors, and be able to calculate image and object heights, distances, and magnifications. Spherical Mirrors: concave and convex mirrors. You must understand the differences between these two kinds of mirrors, be able to draw ray diagrams for both kinds of mirrors, and be able to solve the mirror equation for both kinds of mirrors.

Images Formed by Spherical Mirrors Spherical mirrors are made from polished sections cut from a spherical surface. The center of curvature, C, is the center of the sphere, of which the mirror is a section. C Of course, you don’t really make these mirrors by cutting out part of a sphere of glass.

The radius of curvature, R, is the radius of the sphere, or the distance from V to C. The center of the mirror is often called the vertex of the mirror.

The principal axis (or optical axis) is the line that passes through the center of curvature and the center of the mirror. R Principal Axis C V The center of the mirror is often called the vertex of the mirror.

Paraxial rays are parallel to the principal axis of the mirror (from an object infinitely far away). Reflected paraxial rays pass through a common point known as the focal point F. C V F

The focal length f is the distance from P to F The focal length f is the distance from P to F. Your text shows that f = R/2. R f C P F

Reality check: paraxial rays don’t really pass exactly through the focal point of a spherical mirror (“spherical aberration”). C V F

If the mirror is small compared to its radius of curvature, or the object being imaged is close to the principal axis, then the rays essentially all focus at a single point. C V F We will assume mirrors with large radii of curvature and objects close to the principal axis.

In “real life” you would minimize aberration by using a parabolic mirror. V F