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Practice 15A Answers. 18.5° a) 27.5° b) glycerine (n = 1.47) c) 12.5° 1.47. Physics 15.1 Refraction of Light and Snell’s Law. What do you notice a bout the pencil?. I. Refraction. Def – The bending of light as it travels from one medium to another.
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Practice 15A Answers • 18.5° • a) 27.5° b) glycerine (n = 1.47) c) 12.5° • 1.47
Physics 15.1Refraction of Light and Snell’s Law What do you notice about the pencil?
I. Refraction • Def – The bending of light as it travels from one medium to another. 1. Must be at an angle other than 90° 2. If 90° then no refraction 3. Occurs when light’s velocity changes • Variables 1. Θi = angle of incidence 2. Θr = angle of refraction
C. Velocity Changes 1. cause light rays to speed up or slow down 2. Situations a. High speed lower speed Result = Light is bent towards the normal
Light is bent away from the normal b. Low Speed higher speed Result =
Concept Question When trying to catch a fish, should a pelican dive into the water horizontally in front of or behind the image of the fish it sees? *Answer: Behindof the image, because the light entering the water slows down and is bent towards the normal. Alaskan Natives
II. The Law of Refraction • Index of Refraction – ratio of speed of light in vacuum to speed of light in a medium. • Formula n = c / v a. n = index of refraction b. c = speed of light in vacuum c. v = speed of light in medium • Table 15-1 D. Explains a prism
III. Snells’s Law • Def - the relationship between the angle of incidence and angle of refraction of two materials having different index of refraction. B. Formula n1 sin(Θ1) = n2 sin (Θ2) C. Variables 1. n = indexes of refraction 2. Θ = angles of the rays
Ex: A light ray traveling through air strikes a piece of carbon disulfide at an angle of 25.0° to the normal. Find the angle of refraction. 15.0°