Wrapping Things Up

Reflection and the Ray Model of Light

Objective:

Students will learn about how light and the relationship of an objects distance from a mirror affects an image’s reflection.

Timeline:

First Period – PowerPoint and lab activity

Second period – Assessment

5 Questions for the Final

1.      If a ray of light could be observed approaching and reflecting off of a flat mirror, then the behavior of the light as it reflects would follow a predictable law known as­__________?

a.       Law of Reflection

2. A ray of light is incident towards a plane mirror at an angle of 30-degrees with the mirror surface. What will be the angle of reflection?

b.      The angle of reflection is 60 degrees. (Note that the angle of incidence is not 30 degrees; it is 60 degrees since the angle of incidence is measured between the incident ray and the normal.)

3. The image of an object as formed by a plane mirror is located          .

a.  on the mirror surface                          b.  in front of the mirror surface

           c.  behind the mirror surface                  d.  any of the above, depending on the object's location

4. If Suzie stands 3 feet in front of a plane mirror, how far from the person will her image be located?

            a. Answer = 6 feet
Suzie (the object) is located 3 feet from the mirror. Suzie's image will be located 3 feet behind the mirror. Thus, the distance between Suzie and the image will be 6 feet.

5. Rose Inhatt stands between a set of parallel plane mirrors (M₁ and M₂) as shown in the diagram below. There is a flower on Rose's hat that is located a distance of 0.4 m from M₁ and a distance of 1.0 m from M₂. Since the mirrors are parallel, Rose will see an infinite number of images of the flower as she looks in mirror M₂. These images stretch towards infinity. Some of the images are closer to the mirror than others.

Determine the distance between mirror M₂ and the...

a. ... nearest image ____________

b. ... second nearest image____________

c. ... the third nearest image ____________

                a. 1.0 m, 1.8 m, and 3.8 m