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Critical angle

Exercise and reference answers

Questions
  1. Question
    At the critical angle, the angle of refraction is
    Choices
    1. 0°
    2. 45°
    3. 90°
    Correct choice
    90°
  2. Question
    Total internal reflection occurs when i is
    Choices
    1. greater than the critical angle
    2. less than the critical angle
    3. exactly zero
    Correct choice
    greater than the critical angle
  3. Question
    The critical angle of diamond is about
    Choices
    1. 48.8°
    2. 24.4°
    3. 90°
    Correct choice
    24.4°
  4. Question
    Total internal reflection requires light to travel
    Choices
    1. rarer to denser
    2. through a vacuum
    3. denser to rarer
    Correct choice
    denser to rarer

Explanation

At the critical angle the refracted ray grazes the surface at 90°. Source: syllabus Physics Part II, Ch 9 Ray Optics and Optical Instruments.
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