Here is my mathematic simulation for Snell’s Law.

https://vspace.vassar.edu/xythoswfs/webview/fileManager.action?stk=6DF28C68D0C77DF&entryName=%2Fmalaird

“Snell’s Law for Dielectrics”

Here is a link to my Mathematica simulation exploring eq. 4.86 in Griffiths, or “Snell’s Law for Dielectrics.” I plotted the equation for several incident angles in three cases: equal permittivites, e1>e2, and e1<e2. It seems that there is no analogous critical angle/total internal reflection in the dielectric version of Snell’s law.