Refraction Chapter 15 Refraction Refraction The bending of

Refraction Chapter 15

Refraction • Refraction: The bending of light as it travels from one medium to another • Refraction occurs when light’s velocity changes • The speed of light varies with the medium

Refraction Θi = Angle of Incidence Θr = Angle of Refraction

Index of Refraction • Index of Refraction = speed of light in vacuum speed of light in medium

*Only valid for light with wavelength of 589 nm in a vacuum (p. 564)

Snell’s Law determines the angle of refraction nisin(θi) = nrsin(θr) ni = Index of refraction of first medium nr = Index of refraction of second medium θi = Angle of Incidence θr = Angle of Refraction

Bending relative to the normal • When light passes from a medium with a low index of refraction to a medium with a high index of refraction, the ray bends toward the normal • When light passes from a medium with a high index of refraction to a medium with a low index of refraction, the ray bends away from the normal

CATBEAR trying to catch a fish!!!

Sample Problem (p. 567 #4) • Sunlight passes into a raindrop at an angle of 22. 5° from the normal at one point on the droplet. What is the angle of refraction?

Sunlight into a raindrop • Will the ray bend away from the normal or towards the normal? – Low n to high n, the ray will bend toward the normal θi θr

Use Snell’s Law