So welcome back to the final lecture, of course, and to be honest, I can already congratulate you
because you made it through the most difficult parts of this course and does last lecture very short
and also very easy.
So what we have discussed so far is we have started with considering electrode and electromagnetic waves
in a vacuum.
So there's more light than we have discussed.
A special case of Electrostatic and Magneto's static's, which considered time independent fields.
And then in the last section, I told you that we discussed the most general case, which meant we did
not consider a vacuum and we did consider time dependent fields.
However, we still considered kind of a vacuum.
So what we did is we took a vacuum and then we positioned some charges and some currents inside of this
vacuum.
And of course, what you can do is you can you can build every piece of metal, for example, a metal.
You can take every single electron in this metal and calculate that in the -- potentials and come
up with the solutions, however, and that it consists of out of so many atoms and especially electrons,
it's just impossible to do so in this section.
I will show you a trick how you can consider the Maxwell's equations in matter.
So here we will not actively consider the electrons in the metal, for example, but we will separate
them from the actual electrons or charges and currents that we want to consider.
So we take the matter, the metal, for example, like a background and separate its influence from
the actual charges and currents that we want to consider.
And by using this trick, we also introduced the electric polarization and the magnetization and then
we finally come up with Maxwell's equations in matter.
And as you will see, they look almost the same as the Maxwell's equations in vacuum.
So you can really take most of the results that we had previously and just carry them over to matter.