Today we learned more about refraction, which was incredibly confusing, in my opinion. Refraction is
the changing of wave speeds due to changes in wave media, and is
dependent on how optically dense the medium is. The main thing we
focused on was Snell's Law, which stated that the index of
refraction of a ray of light before it changes media, multiplied by the
sine of said light's angle of incidence would be equal to the index of
refraction of the light when it changes media, multiplied by its angle
of reflection (did that even make sense?). The equation for Snell's Law
is n1sinθ1 = n2sinθ2 (θ
= theta). In order to find the index of refraction, you divide the
speed of light by the speed of light in the medium ( n = c÷v). Also, if
you have the index of refraction of a medium, you could use the equation
to find the speed of light in the medium (v = c÷n). For example, you
were trying to find the speed of light in glass, you would take the
speed of light and divide it by glass' index of refraction, which is
1.5. So you would do 3 x 10^8 ÷ 1.5, to get 2 x 10^8 m/s. We also
learned about critical angles, and how to find them with this equation: sinθc = n2 ÷ n1. With your knowledge of what the critical angle is, you can find what the total internal reflection is, which is when the light's reflecting inside the medium.
When the ray of light changes from a fast medium to a slow medium, the light will bend towards the normal (perpendicular to the surface). However, when the ray of light moves from a slow medium to a fast medium, the light will bend away from the normal.
We also learned the differences between diverging lenses and converging lenses. A diverging lens is when multiple lights are being shined into a lens, and they are all refracted away from each other. A converging lens is the opposite, and when multiple lights are shined into them, the rays of light refract and converge at a focal point. Lastly, we learned about two types of rays. The first ray is a parallel ray, which is from the object being parallel to the optic axis through the focal point on the other side. A focal ray, is from the object through the focal point on the object's side through the lens, then parallel.
Those last two pictures really help to explain diverging and converging lenses. Your diagram is also really helpful in your explanation of the concept of angle of incidence equals angle of refraction. As always, good use of pictures.
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