From a user who "doesn't know" anything about Maxwell's equations. How to explain simply the behavior of a transparent glass of a microwave oven? Lets the light pass ... but blocks the "dangerous" "radiation" emitted by a powerful generator of electromagnetic waves (~ 1 kW). How's it going ? How to explain the manufacture of this glass slab?
Thanks to all contributors and comments. Below my answer at the question. (not complete ...) I don't know if it is usefull, but I hope so.