# What is the largest theta can be if the tube is in water?

## Homework Statement

Light enters a solid 90 degree angled tube made of plastic having an index of refraction of 1.60. The light travels parallel to the upper part of the tube. which is horizontal You want to cut the corner of the tube so that all the light will reflect back into the tube after it strikes that face. a) what is the larget theta can be (theta is the angle from the top) if the tube is in air? b) what is the largest theta can be if the tube is in water?
*diagram attached

## The Attempt at a Solution

I could not find the material related to this question in the book.

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G01
Homework Helper
Gold Member
You must show some work to get help on these forums. To get you started, since you said you couldn't find the material, try to read up on Snell's Law and Critical Angles.

I found the critical angle, which is the largest the angle could be without total internal reflection. But the question askes what is the largest the angle can be?

I got 38.7 degrees and 56.2 degrees.