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# Physics angle help watch

1. Hh g
2. (Original post by M12S)
A diagram shows a ray of light being reflected by a prism. The critical angle of the prism is 42. Explain if the side xy needs to be silvered like a mirror to cause this reflection.
(The prism is a triangle left corner is a right angle z line to the right is y and above z is x.)

Pls help
This question is asking about total internal reflection. You know that when the incident ray has an angle larger than the critical angle,( 42° in this case), total internal reflection occurs, even when a prism is used.

I'm guessing the diagram contains something similar to this?
Spoiler:
Show
If so, like the diagram indicates, the incident ray will be 45° from the normal, which is bigger than 42°, therefore causing there to be total internal reflection without a silvered surface.

I hope this is enough for you to give your own explanation on whether a silvered surface is needed.

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Updated: February 2, 2016
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