critical angle

Definition: The angle or greater, measured at the interface between a denser medium and a less dense in the same plane as the incident light, at which total internal reflection takes place - i.e. light is reflected back into the medium. * Sin / = n1/n2 where / is critical angle, n1 is the refractive index of the less dense medium, n2 is the refractive index of the denser medium. * For glass-to-air interface, the critical angle is around 41<.

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