Refractive Index |
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The change in the direction of light as it passes from one medium to the next is a function of the speed of light in that medium. As shown at the left, light crossing into a region of higher refractive index (going from air to glass) is bent toward normal (the line perpendicular to the interface between the media). Light crossing into a region of lower refractive index (glass to air) is bent away from normal.
Since refraction is a function of the speed (velocities) of light in the two media an index of refraction (nr) may be expressed as follows:
velocity in second medium sin r continued |