Section 15­1.notebook
April 25, 2012
Refraction ­ the bending of a wave disturbance as it passes at an angle from one medium into another.
θr ­ angle of refraction
θi ­ angle of incidence
θ' ­ angle of reflection
When light travels through transparent material such as glass, water, ice, etc; the speed it travels is different than that speed travels in air. The angle that it bends (refracts) at is closer to the normal.
θi
θ'
θi
θ'
glass
air
glass
air
θr
normal
θr
normal
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Section 15­1.notebook
April 25, 2012
Index of Refraction ­ the ratio of the speed of light in a vacuum to its speed in a given transparent medium.
n = c v
index of refraction = speed of light in a vacuum speed of light in medium
Table on page 565 shows indices of refraction for various substances.
The wavelength of light also is a factor in the indices of refraction. The wavelength of light in a vacuum is 589 nm. Other lights have different wavelengths, thus when light passes through a prism a spectrum of light is formed. 2
Section 15­1.notebook
April 25, 2012
Snell's Law ni(sinθi) = nr(sinθr)
index of refraction of the first medium x sine of the angle of incidence = index of refraction of second medium x sine of the angle of incidence
A light ray of wavelength of 589 nm traveling through air strikes a smooth, flat slab of crown glass at an angle of 30.0 degrees to the normal. Find the angle of refraction, θr.
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Section 15­1.notebook
April 25, 2012
Practice 15A ­ all
Section Review ­ all
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