CK-12 Physical Science Concepts - For Middle School

5.54. Law of Reflection http://www.ck12.org

FIGURE 5.122

According to the law of reflection, the an-

gle of reflection always equals the angle

of incidence. The angles of both reflected

and incident light are measured relative

to an imaginary line, called normal, that

is perpendicular (at right angles) to the

reflective surface.

Vocabulary

• image: Copy of an object that is formed by reflected or refracted light.


• law of reflection: Law stating that the angle at which reflected rays of light bounce off a surface is equal to
  the angle at which the incident rays strike the surface.


• reflection: Bouncing back of waves from a barrier they cannot pass through.

Explore More

At the following URL, review the law of reflection and watch the animation. Then fill in the blanks in the sentence
below. http://www.physicsclassroom.com/mmedia/optics/lr.cfm

1. When a ray of light strikes a plane mirror, the light ray __ off the mirror.


2. Reflection involves a change in __ of a light ray.


3. The angle of incidence equals the angle between the incident ray and ____.


4. The angle of __ equals the angle of incidence.


5. The normal line is __ to the mirror.

Review

1. What is an image?


2. Identify the object and the image in theFigure5.123. Which type of reflection formed the image: regular
   reflection or diffuse reflection? How do you know?


3. What is the law of reflection?


4. Label the angle of incidence and the angle of reflection in theFigure5.124.