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Reflection and Refraction of Waves. Important Vocabulary. Incident wave – original wave hitting a surface Angle of incidence – angle of the incident wave Reflected wave – wave that bounces off a surface Angle of reflection – angle at which the wave is reflected
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Important Vocabulary • Incident wave – original wave hitting a surface • Angle of incidence – angle of the incident wave • Reflected wave – wave that bounces off a surface • Angle of reflection – angle at which the wave is reflected • Refracted wave – wave that travels through a medium and is bent by that medium • Angle of refraction – angle at which the wave is refracted
More Important Vocabulary • Converge – waves/rays come together and meet at a certain point • Diverge – waves/rays disperse and move away from a certain point • Convex – curved outward • Concave – curved inward
Law of Reflection • When a ray of light is reflected, the angle of incidence is equal to the angle of reflection θi= θr
Reflection continued… • When an object is reflected, an image is created in the mirror • The image in the mirror is the same distance at which it is reflected
Virtual vs. Real Images • Real Image – waves converge when they hit the mirror • Ex: convex and concave mirrors
Virtual vs. Real Images • Virtual Image – waves diverge when they hit the mirror • Ex: plane mirror
Law of Refraction • Refraction is the bending of waves as it moves from one medium to another medium with a different density • The more dense the medium is, the slower the wave travels • The speed of light in a vacuum is 3 x 108 m/s, so we assume that the speed of light in air is the same because the numbers are so close • c = 3 x 108m/s • c represents the constant of the speed of light
Law of Refraction • The index of refraction is the ratio of the speed of light in a vacuum to the speed of light in the medium n = c/v n = index of refraction c = 3 x 108 m/s v = speed of light in the medium
Law of Refraction • Light bends TOWARD the normal when the optical density is MORE dense • Light bends AWAY from the normal when the optical density is LESS dense n1 = 1 n1 = 1.5 n2 = 1.5 n2 = 1
Law of Refraction • According to the picture and the previous slide, how would you know that water is more dense than air?
Law of Refraction • Snell’s Law – shows mathematical relationship between the angle of incidence and angle of refraction when traveling through different media • (n1)(sin θ1) = (n2)(sin θ2) • n1 = index of refraction in medium 1 • θ1 = angle of incidence • n2 = index of refraction in medium 2 • θ2 = angle of refraction