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Comparatively Speaking: Refractive Index vs. Refraction of Light
By: Anthony O'Lenick, Jr., Siltech LLC
Posted: December 20, 2010
page 2 of 2
According to Wikipedia, the following general rules apply to how light interacts with different materials:
• Light arriving at an opaque surface will be reflected, scattered or absorbed in some combination.
• The color of opaque objects that do not reflect is determined by the wavelengths of light that are scattered. If objects scatter all wavelengths, they appear white. If they absorb all wavelengths, they appear black.
• Opaque objects that reflect light of different wavelengths with different efficiencies look like tinted mirrors with their colors determined by the differences in efficiency.
• Objects that transmit light are translucent (scattering the transmitted light) or transparant (not scattering the transmitted light). If they also absorb (or reflect) light of varying wavelengths differentially, they appear tinted with a color determined by the nature of that absorption (or that reflectance).
• Objects may emit light that they generate themselves, rather than merely reflecting or transmitting light. They may do so due to their elevated temperature, which are then said to be incandescent; as a result of certain chemical reactions, a phenomenon called chemoluminescence; or for other reasons.
• Objects may absorb light and then as a consequence emit light that has different properties. They are then called fluorescent (if light is emitted only while light is absorbed) or phosphorescent (if light is emitted even after light ceases to be absorbed; this term is also sometimes loosely applied to light emitted due to chemical reactions).
A popular example of dispersion of light is a rainbow. A rainbow results when light enters water droplets. It is refracted, totally internally reflected off the back, and refracted again as it leaves. The refractions cause the dispersion effect and a rainbow results. When light refracts, different colors refract through different angles. This dispersion effect produces a rainbow of color.2