So let us summarize what we have learned in this lecture about the early electrodynamics, so we have
learned about double slit experiment, which essentially was the main proof why light must behave as
a wave.
But please also remember, there are some experiments which require light having a particle like properties.
But we will not really focus on these experiments here, these early experiments, which in the end
gave rise to quantum mechanics.
And here we want to go one step back and want to consider only the electrodynamics, which is light
being a wave.
Furthermore, it was already known that there is a concept of magnetism and of charge and that there
are some fields related to to charge and to magnets, which are the electric field and the magnetic
field.
And also there were already some numerical evidences and some laws describing these concepts here.
So these this is the Cullum's law, which describes the force between two charges with respect to their
distance.
So it's one of our square law.
Then we have the impasse law, which describes that you generate a magnetic field by currents or by
moving charges.
In general, however, we have also learned that here we are missing a term because this violates the
continuity equation.
So this was something that one has to keep in mind, but also one has to take care of this missing term.
And then there were other experiments which explained or which point towards the existence, a concept
called induction.
So here we've learned, for example, if you take a wire loop and you put it into a magnetic field back
and forth, you will generate a voltage.
So this induction voltage here, so these are all the laws that were essentially known to be true except
for this missing term.
And also here we have these different quantities and phenomena that were also known to be true.
So what Maxwell now did is he took all of these known facts and all of these evidences and concepts
and put them into four equations.
And these are the Maxwell equations that we want to discuss in the next section.