Greenwood press

108
REFLECTIONS
Light rays reflect from walls at congruent angles. The angle of incidence, 
α,
has the same measure as the angle of reflection, 
β.

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Using reflections in games becomes more complicated, however, in situa-
tions where a ball needs to bounce off two walls. The same relationships regard-
ing reflections exist in these circumstances, but the player will need to focus on
reflections of reflections in order to utilize multiple walls in the attempt. 
For example, suppose the player realizes that he or she cannot get a hole-in-
one by hitting just one wall, as indicated in the above figure. Instead, the player
imagines hitting two walls, the side wall first and then the back wall. In order to
sink the shot, he or she will need to locate the reflection of the hole on the back
wall,
H
′
, and then the location of the reflection of the reflection, 
H
′′
. The player
then aims towards the side wall at the double reflection of the hole, 
H
′′
, and the
ball should follow a path towards the first reflection by hitting the back wall, and
then land in the hole, as shown below. 
The process can get even more complicated with more reflections, such as
what takes place in games like racketball. In such a fast game, it may be difficult
to predict where the ball will eventually land after it has been struck. However,
a general knowledge of reflections can give a player a sense of what direction the
ball will head once it hits the first wall.
The relationship between the angle of incidence and angle of reflection also
informs product designers that full-length mirrors should only be one-half a per-
son’s height. In this type of mirror, the reflection of light from your eye level to
your waistline will angle down towards your toes (see the following figure). This
relationship is true, because the point of contact with your line of sight and the
mirror is at the midpoint of your body, where the angle of incidence is congruent