aka Electrodynamics
https://physics.stackexchange.com/questions/139238/deriving-heaviside-feynman-formula-for-the-electric-field-of-an-arbitrarily-movi/145423#145423
https://physics874.files.wordpress.com/2016/03/feynman-lectures-em-equation1.pdf
Electric motor
https://www.youtube.com/channel/UCPC6uCfBVSK71MnPPcp8AGA/playlists
Electromagnetic theory
https://physics.stackexchange.com/questions/138583/feynmans-proof-for-liénard-wiecherts-potential-of-a-moving-charge