Published 2020-06-28T13:16:00.004Z by Physics Derivation Graph
There are multiple derivations associated with waveguides. However, I don't see derivations focused on waveguides as being connective to any other topic.
Similarly the Navier-Stokes equation for fluids doesn't seem to relate any topics (though I have less experience with this compared to waveguides).
There is probably a "connective derivation" that relates Quantum Mechanics to Statistical mechanics, probably involving the definition of entropy.
Another connection is that Statistical mechanics is related to thermodynamics (again, not clear what derivation would show this).
classical mechanics and astrophysics are based on the same concepts
There should be a relation between (classical motion) and (relativity) since the difference is the assumptions about slow versus fast objects.
Wave-particle duality present in optics relates to atomic theory
the orbit of Mercury relates astrophysics to relativity
thermodynamics connects to quantum mechanics in the black-body radiation experiment
quantum field theory relates relativity to quantum
I don't have insight on how electrodynamics relates to quantum mechanics or how electrodynamics relates to classical mechanics.