20.2. Concave and Convex Mirrors http://www.ck12.org
20.2 Concave and Convex Mirrors
Objectives
The student will:
- Understand how to draw ray diagrams for concave mirrors.
- Understand how to solve problems involving concave mirrors.
- Understand how to draw ray diagrams for convex mirrors.
- Understand how to solve problems involving convex mirrors.
Vocabulary
- concave mirror:A mirror that curves inwards, like the inside of a bowl.
- convex mirror:A mirror that curves outwards, like the top of a dome.
- focal point (orfocus):The point from a spherical mirror or thin lens where parallel rays of light converge.
- real image:An image formed from rays of light converging, that can be projected onto a screen or paper.
- spherical mirror:A curved mirror formed that matches the shape of a slice from a larger sphere.
Introduction
Amusement parks often have Fun Houses with mirrors that distort your image in various funny ways. Even more
commonplace curved mirrors are rear-view mirrors for cars. As the warning shown above states, "Objects in mirror
are closer than they appear." The mirror is curved to allow drivers to see more of the road, but this also distorts the
image.
Using diagrams of the position of the mirror and the object, we can calculate how large the image is, and in what
position it appears to be.
Concave mirrors
This curvature means that the reflection in this bowl-like mirror seems smaller or closer than it really is. The Figure
20.7 shows how a concave mirror reflection differs from a flat mirror. In the flat mirror, the parallel red lines show
the center of the reflection. The reflected rays are symmetry about each of these. In the concave mirror, the same red
lines are at angles perpendicular to the curved surface. This creates an image that is larger than the original object.