Add example for consistency of fresnels equations

[VincentLatko]

No description provided.

[simbilod]

Nice! PML seems a bit thin (2-3 mesh points)

[HelgeGehring]

We might want also to start with a lower resolution, most of the examples in the docs are resolutionwise rather at low resolution to make them run fast (for understanding things) - once we want high precision we can always increase the resolution

[HelgeGehring]

Could you run

pip install pre-commit
pre-commit install
pre-commit run --all

that will format the code (and do it after installing always when you commit)
after that I'm happy to accept the PR :)

[VincentLatko]

I pushed the new version. Also increased the PML thickness. I hope this is better.

[HelgeGehring]

Looks good now!
Probably, now the resolution is a bit too low. We should aim at something like 10 elements / wavelength. That'll probably give a good runtime while representing the physics correctly.
But that's something we can co-optimize as soon as we have the simulation getting started :)