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Home Concept Builders Refraction and Lenses Total Internal Reflection Directions

Total Internal Reflection - Directions

Using the Total Internal Reflection Concept Builder is quite simple. There are three activities, each of which has a unique collection of questions that are not seen in the other activities. In the first activity - To TIR or Not To TIR - you will have to select any diagram for which you believe the provided incident ray will undergo total internal reflection (TIR). You can base your answer on the relative optical density (or light speed or index of refraction) of the two media; assume that the angle of incidence is sufficiently large. You select an answer by tapping on the diagram. Tapping once selects the diagram as an answer; tapping a second time deselects it. You can select as many diagrams as you wish. As long as one or more diagrams is selected, a Check Answer button will appear. If you are satisfied with your answers, tap on the Check Answer button. Your answer will be evaluated and your Progress Report will be updated.

In the second activity - R&R or TIR - you are provided three diagrams showing three different boundary behaviors. The three behaviors are ...

  1. total internal reflection (no refraction).
  2. reflection and refraction with the refracted ray lying along the boundary line .
  3. reflection and refraction; the refracted ray has an angle of refraction less than 90°.

You must match these three types of behaviors to the relationship between the angle of incidence and the critical angle. You can make the match by tapping on the text fields below each diagram. Tapping allows you to toggle through the three choices. Once you have provided a unique match for all three diagrams, a Check Answer button will appear. If you are satisfied with your answers, tap on the Check Answer button. Your answer will be evaluated and your Progress Report will be updated.

In the third activity - Angle is Critical - you are given three diagrams with incident rays having varying angles and being on varying sides of the boundary. You are told either the relative speed of light in each medium, the relative optical density of each medium, or the relative index of refraction of each medium. You are also told the critical angle and provided a protractor to make a measurement of the angle of incidence. You must identify any of the diagrams for which the given incident ray would undergo total internal reflection. You select an answer by tapping on the diagram. Tapping once selects the diagram as an answer; tapping a second time deselects it. You can select as many diagrams as you wish. As long as one or more diagrams is selected, a Check Answer button will appear. If you are satisfied with your answers, tap on the Check Answer button. Your answer will be evaluated and your Progress Report will be updated.

Your goal is to earn "Stars" and to complete one or more activities. Stars are earned when you show success on a particular question. Once you show success on all the questions for a particular activity, you will earn the trophy for that activity.

Concept Builder Teacher Notes