Exam-style question
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Which of the following best describes the critical angle?.
- A.The angle of incidence at which light is refracted at 90 degrees.
- B.The angle at which total internal reflection occurs.
- C.The angle of incidence that results in no refraction.
- D.The angle at which light travels straight through a boundary.
Model answer
What a good answer should say
- The angle of incidence at which light is refracted at 90 degrees.
Explanation
Why this works
The critical angle is defined as the angle of incidence in the denser medium at which the refracted ray travels along the boundary, resulting in an angle of refraction of 90 degrees in the less dense medium.
Common mistake
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