Name: Kim T.
How does the mirror reflects my image? What is the mirror
made of? Why do the words on a paper appear backward when reading them
with a mirror?
Light is emitted from every point on an object in all directions and
travels in straight lines. Some of those rays hit many points on the
mirror. The mirror reflects light at each point according to the Law of
Reflection (The angle of incidence is equal to the angle of reflection with
respect to the normal at the point of interest.)
The rays coming from a single point on the object hit the mirror in
different places and continue to diverge after reflection. If one were to
view these diverging rays, it would appear as if they meet somewhere behind
the mirror. This is called a virtual image. There is no actual image
there, but rather an image that is constructed in your mind.
A mirror is usually made up of a coating of reflective metal, such as
aluminum or silver, deposited on some rigidizer, such as glass. It can
also be a highly polished metal.
The words on the paper are being reflected EXACTLY as you sent them. Let
us say you are wearing a sweatshirt with the capital letter 'L' printed on
it. As you would normally read it, it has a vertical stroke on the left
and a short horizontal leg going to the right at the bottom. But the way
you sent the information to the mirror is with the vertical stroke on the
right and the horizontal leg going to the left. That is exactly how the
mirror reflects the light back to you. There is no right-left nor up-down
switching involved. The message you sent (as if you were on the inside of
the sweatshirt) is the message received. The mirror did not change any
letters whatsoever. The reason why they appear backwards is because that
is how you sent the information TO the mirror.
Nathan A. Unterman
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Update: June 2012