Total Internal Reflection

The Total Internal Reflection Concept Builder includes three activities that target student understanding of the requirements for total internal reflection. In the first activity - To TIR or Not To TIR - learners are provided information about the relative speed of light, optical density, or index of refraction value of two adjoining media. They are provided a diagram with an incident ray in one of the media and must determine if total internal reflection (TIR) will occur if the angle is sufficiently large. In the second activity - R&R or TIR (short for Reflection and Refraction or Total Internal Reflection) - learner are provided three diagrams. One shows total internal reflection; one shows reflection and refraction with the refracted ray lying along the boundary line; the final diagram shows reflection and refraction (but not along the boundary line). Learners must compare the value of the angle of incidence to the critial angle for each of these three boundary behaviors. In the third activity - Angle is Critical - learners are provided three diagrams and are told in which medium light travels the fastest, which medium is most dense, or which medium has the greatest index of refraction value. From the given information (and the presence of the incident ray in one of the two media at varying angles of incidence), learners must decide which incident ray would undergo total internal reflection. The Concept Builder includes 36 questions organized into 12 different Question Groups and spread across the three different activities. Question-specific help is provided for each of the questions. Use of this Concept Builder with our Task Tracker system allows teachers to track student progress.