Protractor - Law of Reflection (Laura Silverman)
Author
Laura Silverman, 7th grade Science, Mulholland Middle School
Principles
The angle of reflection is equal to the angle of incidence.
Standards
Physical Principles in Living Systems (Physical Sciences)
7.6. Physical principles underlie biological structures and functions.
g. Students know the angle of reflection of a light beam is equal to the angle of incidence.
Materials needed
paper protractor
sheet protector
small mirror with flat edge (no border)
maglight (the smaller the better)
Procedure
Have students pick an angle of incidence, then demonstrate that the angle will be the same at the other side.
Explanation
The mirror provides a perfect reflection and bounces the light at an equal angle from the normal line drawn perpendicular to the mirror edge.
Questions
What is the angle of the incident light from the flashlight to the mirror?
What is the angle reading on protractor from the reflection from the mirror?
Are these angles the same?
Everyday examples of the principles illustrated
Light bounces off mirrors in solar panels and in telescopes. Also you can see sunlght reflecting from car windows, building windows, and other reflective surfaces.
Photos
.
Movies
Here is a more elaborate set up using a light box to generate the light beam.
.
References
Here is a website of this lab from the College of Micronesia:
Here is another site from University of South Carolina