F cl 3x108 5x10-17 6x1024Hz. Light traveling in a uniform substance or medium propagates in a straight line at a relatively constant speed unless it is refracted reflected diffracted or perturbed in some other manner. Ice n 131.
Water n 133.
History at your fingertips. F cl 3x108 5x10-17 6x1024Hz. Where c - the speed of light in vacuum v - the phase velocity of light in the medium n - refractive index. N V Where.