Posted by **sophie** on Monday, April 6, 2009 at 10:54pm.

A beam of light passes from air to ethanol, with index of refraction of 1.36. If the angle of incidence ( 1) is 30.0 degrees, then calculate the angle of refraction, after light passes through ethanol and enters into air.

A. 15.3 degrees

B. 21.6 degrees

C. 30.0 degrees

D. 39.8 degrees

I tried it and got C??

- Physics...please help -
**Anonymous**, Wednesday, December 15, 2010 at 6:15pm
its B

- Physics...please help -
**Sebastien Tides**, Friday, November 4, 2016 at 6:30pm
The answer can be found using the following method:

Index of refraction 1[wtf is this?: air = 1.00] * Sin(30)[wtf is this?: 30 degrees]

all of that is equal to =

Index of refraction 2[wtf is this?: 1.36 {water is 1.33 just fyi}] * Sin(??) [wtf is this?: what you are asked to find]

Okay now that I've laid that out for your lazy procrastinating undisciplined drudering self:

1.00 * Sin(30) or 1.00 * 0.5, because the Sin(30 degrees) = 0.5

So the 1.00 * 0.5 = 1.36 * some number that is the same as saying Sin(??some angle??)

Let me grab my graphing calculator you slovenly procrastinating not doing what you are supposed to person...

(1.00*0.5)/1.36 = 0.3676470588

BUT WAIT, THERE'S MORE!

That isn't the angle you are looking for.

Remember how I took the sin of 30 degrees and got 0.5? This last number is the same kind of dude. We have to Sin^-1(0.3676470588) to find our angle. [WTF does that mean?: it means inverse Sin (bla number) = an angle]

And just you know, since you don't study like you should, that bla number is actually a fraction between 0 and 1 which represents the height of the triangle in a unit circle. If you don't know wtf that is, you need to catch up and handle yourself, or you're going to be very disappointed in yourself soon...

HANDLE YOUR BUSINESS!

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