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ICSE Question Bank
2024Q4(iii)(b)(3)Refraction of Light at Plane Surfaces
IdentificationEasy1 mark
4(iii)(b)

The diagram below shows the path of a blue ray through the prism :

Figure for this question

Which colour should replace the blue ray, for the ray to undergo Total Internal Reflection?

Topic: Critical angle and colour

Question wording verified against source paper

Answer

Solution diagram
Solution diagram
Exam answer

Indigo or violet.

Explanation

These colours have smaller critical angles than blue, so the same incidence angle can exceed the critical angle and produce total internal reflection.

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