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Q & A: mirror basics

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Most recent answer: 10/22/2007
Q:
What are the properties of mirrors?
- Hansol
M.S 158, Flushing NY US
A:
Here's a really basic general property: a light ray that strikes a mirror at an angle, will reflect off at the same angle. (angle of incidence equals angle of reflection.) That means that patterns in the light are preserved, unlike when light bounces off ordinary surfaces in all different directions.


Some of the consequences of the basic law follow. A mirror that is concave (the mirror side is on the inside of the curve) will focus light rays and form a real image of the object. For light that comes in from a long ways out, all the beams get focused to a single point called the focus point - very similar to how a magnifying glass works.
for a convex mirror (the mirror side is on the outside of the curve) the light rays form what is called a virtual image. Virtual images look like that are behind the mirror but are not formed by any actual light rays.

James

(published on 10/22/2007)

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