Mirror, Mirror

Introduction: In this activity, students test the Law of Reflection based on experimental evidence. However, the back-silvered glass mirrors present a twist. As light travels from air into glass, it changes direction (refracts), reflects off the shiny metal back coating, then changes direction again upon emerging from the glass. The reflected ray may not match up with students' expectations, and offers them a challenge to work out what happened as the light traveled into and out of the mirror.