Total Internal Reflection
1 mark · EasyWhich of the following conditions must be met for total internal reflection to occur at a glass–air boundary?
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Correct option: The angle of incidence must be greater than the critical angle and light travels from glass into air.
Common mistakes: Choosing the answer referring to air to glass, which is incorrect.
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Marking points
B1 · 1 mark · Correctly selects: The angle of incidence must be greater than the critical angle and light travels from glass into air.
Worked solution
Total internal reflection only occurs when the angle of incidence in the denser medium is greater than the critical angle and the light travels towards a less dense medium (glass to air).