20.1. Light as a Ray and the Law of Reflection http://www.ck12.org
FIGURE 20.5
An image formed with a plane mirror.Diagrams such asFigure20.5 are called ray diagrams.Ray diagrams are visual aids showing the object’s position,
some of the rays forming the image, and the image itself.
To further investigate how a plane mirror forms images see this link: http://www.youtube.com/watch?v=2ek0EsEMT
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Check Your Understanding
True or False: When standing straight, in order to see your reflection (from your head to your toes), you need a
mirror that is at least equal to your height.
Answer:False. Using the Law of Reflection, we can deduce that a mirror the height of your body is not needed. In
the figure below we see that a ray of light from your toes will reflect from a point about half the height of your body.
It is actually half the distance from your toes to your eyes. See if you can convince yourself that a mirror exactly
half your height is sufficient to see your entire body. Don’t forget to consider the rays of light from the top of your
head to your eyes!