I would like to "master" polar coordinates and spherical polar coordinates. In the sense, I would like to become as well versed with them as I am with cartesian coordinates.
I have gone through many physics books, Boas, Marsfield, Griffiths, but they really don't get into this stuff deep enough. For instance, I just don't have any intuition for unit vectors (r, theta), the fact that they can keep changing as a particle moves along a certain trajectory troubles me greatly. I simply cannot "see" these vectors.
In truth, I may be able to solve problems, but I lack understanding and insight.
Hence, this request. My ultimate goal: (1) To be able to truly appreciate the full power of these coordinate systems -- when, why, and how to use them, especially in the context of Classical Mechanics, Electrodynamics, and Quantum Mechanics.
In other words, I would appreciate book(s) that treat(s) the above coordinate systems with great rigour, so that I may be able to invoke them with impunity in the areas of physics. I do not want any book(s) that treat the above with "lazy" rigour as I see most physics books do.
So, please give me titles of books that truly discuss the above in detail, and not just burn through them without giving them their due diligence, as most applied mathematics/mathematical physics/engineering books I know of.
I have yet to find a book discussing spherical coordinates in the rigorous manner you are asking for. Regardless I can share other books/resources that discuss this coordinate system and apply it to quantum mechanics. Seeing some more images and calculations might show the spherical coordinate system's usefulness and help your intuition.
I would advise you to solve the Schrödinger equation for a hydrogen atom with cartesian and spherical coordinates separately. I believe this would convince you why spherical coordinates are easier to use for spherical symmetric systems.
Here is a general calculus book, definitely not in debt or rigorous. Either way it might be a different point of view.
Here are some more chemistry-related books that show spherical harmonics and or hydrogen-like orbitals:
These websites might also be helpful:
As a final note, the notation for the azimuthal and polar angles is not standard. Mathematicians typically use $\theta$ and $\phi$ respectively while Physicists do it the other way around.