Does EM wave amplitude change crossing media boundaries?

[BrooklynBees]

What happens to the amplitude of an electromagnetic wave when it crosss from a less dense to a more dense medium?

I couldn't find it anywhere on the net.

 

[lzkelley]

Less dense to more dense isn't specific enough for EM waves. If the material is close enough to electrically neutral (even in the presence of strong EM fields), then the waves wil continue unchanged.
If your talking about light, it gets even more complicated.