Identifying substances using critical angle

[Derosion]

Homework Statement

The critical angle for diamond is 24 degrees. The critical angle for benzene is 42 degrees. Which of the following angles of incidence would results in total internal reflection in diamond and which in benzene?

A)20 degrees B)25 degrees C)30 degrees D)35 degrees E)40 degrees F) 45 degrees

Homework Equations

Don't really know tbh.

The Attempt at a Solution

I was away for a couple of days so I'm a bit lost. These were questions that were given after I completed a lab.

If you guys would be kind enough to help me out, that would be great.

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Another question I have as well

Homework Statement

If the critical angle of a substance if 47 degrees, identify the substance. Use table 1, p. 437

Well, I can't show you guys my table. But here's a site where it shows you the table (indexes of refraction)
http://hyperphysics.phy-astr.gsu.edu/hbase/tables/indrf.html

Homework Equations

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The Attempt at a Solution

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Thanks guys :)!

 

[omoplata]

The http://en.wikipedia.org/wiki/Critical_angle" . (Click on the links)

Use Wikipedia