# Snell's law

1. Oct 28, 2007

### sinz

Snell's law[SOLVED]

1. A ray of light travels from air(which is given to be 1.0003 I also had it be N1) into a liquid. The ray is incident upon the liquid(n2) at an angle of 30 degrees. The angle of refraction is 22 degrees.
Indices of Refraction.
Medium. . . .N
Vacuum......1.00
Air.. . . . ....1.0003
Water.........1.33
Ethanol.......1.36
Crown Glass.1.52
Quartz........1.54
Flint Glass---1.62
Diamond-----2.42

2. n1 X sinO1= n2 X sin02

3. n1 X sinO1= n2 X sin02 Alright so I am given the O1, O2, N1, but not N2 so I will plug in the numbers.

1.0003 X sin(30)= N2 X sin(22) Then I continue to do the math
1.0003 X -0.988031624 = N2 X -0.00885130929
-0.988328033= N2 x -0.00885130929
so N2= 111.658965

My main problem is that the math doesn't any of the mediums we are given. Did I make a mistake in my work or is the book wrong? I have gone over this many times with myself.

Last edited: Oct 28, 2007
2. Oct 28, 2007

### Hurkyl

Staff Emeritus
Those values for sin look very wrong. You should have memorized the sine of 30 degrees, and should have a rough idea about the sine of 22 degrees, so you should be able to recognize that your calculation is wrong.

3. Oct 28, 2007

### sinz

So then it would become
1.0003 x .5 (I knew something looked wrong should not use google calculator ever again.)= n2 X 0.374607
.50015= N2 x 0.374607
Divide by 0.374607
N2= 1.33

Thank you!

4. Oct 28, 2007

### Hurkyl

Staff Emeritus
Don't forego google calculator, just use it correctly! This is a lesson in always writing your units.

Try asking it "sin 30 degrees".

Without the angle marking, it assumed radians.

5. Oct 28, 2007

### sinz

Oh. Well thank you! Units are very important I just tried google calculator again and wrote radians got the same answer then I did degrees and got .5, Thank you!

Units are important.