# Light - Angle of Deviation...

by futb0l
Tags: angle, deviation, light
 Sci Advisor HW Helper P: 2,586 I believe it's called Snell's Law: $$\frac{\sin \theta _1}{n_1} = \frac{\sin \theta _2}{n_2}$$ $\theta _1[/tex] is the angle of incidence, [itex]n_1$ is the index of refraction of the first medium (i.e. if it's going from water to plastic, water is the first medium), $\theta _2$ is the angle of deviation (wait, I don't remember it being called "angle of deviation," I thought it was angle of refraction or something, oh well...) and you can guess what $n _2$ is. I believe you have 3 of these values, so you can find the fourth. And don't take my word, look up this law and make sure I have it right (I can't imagine it being any different, but you never know). EDIT: Oh, and in case you needed, the third value that isn't explicitly given to you is the index of refraction of air, which I'm pretty sure is 1, but look that up too.
 P: n/a i know how to calculate the angle of refraction, but i am still not sure on how to calculate the 'angle of deviation' which is quite confusing. btw, Snell's Law is suposed to be... $$n_1 \sin \theta _1 = n_2 \sin \theta_2$$
 P: 1 Hey, i dont know how long ago this questions from but the answer 19 is right! This is how you do it: the formula as you said is $$n_1 \sin \theta _1 = n_2 \sin \theta_2$$ what you do is $$n_1(1) \sin ( 65 = n_2(1.55) \sin \theta_2$$ and then you get Sin(65) divided by 1.55 = refractive angle the refractive angle is 35 Your mistake was you just subtracted 35 from 65 and got 30 you should have subtracted: SIN (65) - SIN(35) And then gotten the inverse sin which would have given you 19.4 which is 19 degrees :D yay!