Ray Tracing &
Converging Mirrors
[Non-animated
version of this page]
The Law of Reflection and Curved Surfaces
The Law of Reflection works for a curved surface just as it does
for a flat surface:
- First, construct the normal to the surface where the ray
strikes it (just imagine that there is a short plane mirror at
that location, as in section 1, and draw a normal to it)
- Then measure the angle of incidence
- Now construct the angle of reflection equal to the angle of
incidence on the other side of the normal.
The Law of Reflection and Converging
Mirrors
With a converging mirror, however, the Law of Reflection has a
three of convenient side effects that make drawing ray diagrams for
converging mirrors very quick and easy:
- If a ray traveling parallel to the axis of the mirror strikes
the mirror, it will be reflected (thanks to the Law of Reflection)
through the focus of the mirror.
- If a ray passing through the focus of the mirror strikes the
concave mirror, it will be reflected (thanks to the Law of
Reflection) parallel to the axis of the mirror.
- If a ray of light passes through the center of curvature of
the miror, it will be reflected back through the center of
curvature.
These three ideas are all that you need to know to easily and
conveniently locate the images formed by a concave mirror.
[Non-animated
version of this page]
last update September 20, 1999 by JL
Stanbrough