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Question
In the diagram, a narrow beam of white light is incident on a right-angled isosceles prism. The critical angle of the material of prism for the yellow colour of white light is 45°. Complete the diagram to show the path of blue, yellow, and red colours of white light till they emerge out of the prism.

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Solution
The completed diagram is shown below:

The critical angle for yellow light is given to be 45°. Since μblue > μyellow and μred < μyellow so the critical angle for blue light will be less than 45° and for red light will be more than 45°.
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