![]() ![]() And, let's say we're able to measure the angles. So this is some unknown material where light travels slower. So it's in a vacuum, so let's add some light traveling like this, and once again, if you view the, just to get whether it's going to bend inward or bend outward, the left side is going to get out first, so it's going to travel faster first, so it will bend inwards when it goes into the faster material. Just because last time we went from the faster to the slower. Actually, let me make it interesting, let me make the light go from the slower medium to the faster medium. This is a vacuum right over here, or pretty darn close to a vacuum, and I have light coming in at some angle, I have light coming in at some angle, just like that, let me drop a vertical, so it's coming in at some angle. Let's say that we have, just to make things simpler, let's say that I have some surface over here, so this is some unknown material, and we're traveling in space, we're on the space shuttle, and so this is a vacuum. So, Snell's Law goes with our little car driving into the mud analogy, it's going to be a narrow degree, it's going to come inwards a little bit closer to vertical. Now, to solve for theta, you just have to take the inverse sine of both sides of this. On this side, we're just left with sine of theta two, on the left hand side I get, I'll switch colors, 0.4314 is equal to sine of theta two. ![]() Now, we can divide both sides of the equation by 1.33. The fraction index for air is this number right over here: 1.00029, so it's going to be 1.00029 times the sine of 35 degrees is going to be equal to the refraction index for water which is 1.33. And we know what the refraction index for air and for water is, and we just have to solve for theta two, so let's just do that. That just tells us that the refraction index for the first medium, so that is air, the refraction index for air times the sign of the incident angle, in this case it's 35 degrees, is going to be equal to the refraction index for water times the sine of this angle right over here, times the sine of theta two. What is this? So this is just straight up applying Snell's Law and I'm going to use the version using the refraction indices since we have a table here from the flexbook on the refraction indices. I want to figure out the angle of refraction. So it will then bend a little bit, and I want to figure out what this new angle will be. So it will refract a little bit, it will bend inwards a little bit since this outside is going to be in the air a little longer if you buy into my car travelling into the mud analogy. What I want to know is what the angle of refraction will be. So, relative to the perpendicular, it has an incident angle of 35 degrees. And I know that I have a light ray coming in with an incident angle of. So this right here is the surface of water. That is the surface, let me do that in a more appropriate color, that is the surface of the water. So let's say that I have two media, I guess, the plural of "mediums." So let's say I have air right here. Repeat the procedure for each of the incident rays, recording angle of incidence and corresponding angle of refraction in the table.- As promised, let's do a couple of simple Snell's Law examples.Measure the angle of refraction with a protractor and record in the table. ![]() Carefully mark in the angle of refraction, r, between the refracted ray and the normal.
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