Additional Info

• ID Code: L2-01
• Purpose: Demonstrates reflection from a plane mirror
• Description:
  This demonstration shows that the angle of incidence is equal to the angle of reflection. A bright white light source is directed through a baffle with several slits, producing a set of rays. Lenses are used to collimate these rays, and they are then reflected off of a long plane mirror. If the lenses are adjusted such that the incoming rays are approximately parallel, the reflected rays will be as well.

  Engagement Suggestion

  Optionally, you can use slits with colorful filters to show that this is good for all colors. Challenge students to predict what will happen if you switch to the color filters – will different colors reflect at different angles? Why or why not?

  Background

  Unlike light diffracted through a lens or prism, reflected light from a surface is unaffected by the frequency of the light. The reflection off of a flat mirror is dependent only on the angle the light strikes at. Thus, there should be no chromatic aberration in a reflecting telescope, one reason they are valuable for astronomical use.
• Availability: Available
• Loc codes: FS1