Oil-Mixed Portland Cement Concrete

Some insight into Feynman’s approach to electromagnetism

“…Instead, he does not compute the magnetic field, limiting himself to a qualitative discussion. As stated, this is analogous to the approach of [6][7][8][9][10][11], although the authors of these references directly compute the magnetic field, while Feynman, coherently with his declarations, computes the potentials first, and then derives the fields.…”

“…After that, condensers (adopting the variational technique also introduced in the lectures) and dielectrics are discussed. As typical of the Hughes lectures, some off-topic remarks are scattered here and there, concerning in particular the atomic bomb and a possible intuitive explanation of the exclusion principle 6 .…”

“…Indeed, from an advanced point of view, a popular and elegant alternative to introduce electromagnetism is to make it descend from relativity rather than the other way round, which is the standard historical route. Already starting from Page's pioneering paper in 1912 [6], it became clear that magnetic fields could be understood as relativistic effects due to relative motion with respect to electric charges. In particular, the magnetic field of a uniformly moving point charge (and in fact, the whole of magnetostatics if the superposition principle is assumed) can be obtained by boosting the Coulomb field of a static charge [6][7][8][9][10][11].…”

“…Already starting from Page's pioneering paper in 1912 [6], it became clear that magnetic fields could be understood as relativistic effects due to relative motion with respect to electric charges. In particular, the magnetic field of a uniformly moving point charge (and in fact, the whole of magnetostatics if the superposition principle is assumed) can be obtained by boosting the Coulomb field of a static charge [6][7][8][9][10][11]. Also, the fields of accelerating charges, including radiation, can be derived from the knowledge of the Coulomb field and relativity, with a few more assumptions, i.e.…”