Start the above video at 8:15. How does the phase velocity affect the apparent velocity of light in a medium? From my understanding a phase shift will change the direction of light, but how does this affect the "apparent" velocity?


closed as too broad by Carl Witthoft, user36790, Kyle Kanos, Sebastian Riese, Gert Nov 16 '15 at 14:40

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  • $\begingroup$ see the Snell's law wiki $\endgroup$ – user46925 Nov 16 '15 at 10:13