"An electric field can be described by four field quantities ... The electric field intensity \overrightarrow{E} is the vector field used in electrostatics when charge is at rest in free space and is defined as the electric force on a test charge. The electric displacement vector \overrightarrow{D} (also called the electric flux density or displacement flux) is a vector field used in studying the electric fields inside material objects. Similarly, magnetic field intensity \overrightarrow{H} is a vector needed in discussing magnetic phenomena, that is the field generated at a point in free space by steady or time-varying electric currents in a source; it is related to the magnetic force acting on a moving charge. The magnetic flux density \overrightarrow{B} is useful in the investigation of the magnetic fields within material objects where the material modifies the field intensity."
In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interactions of atoms and molecules. Electromagnetism can be thought of as a combination of electrostatics and magnetism, which are distinct but closely intertwined ph
"In this corner, static electricity: the spark... In that corner, magnetism: the trusty realignment of the compass needle. Two different forces? No. The difference is only superficial, because both interactions arise from a single source, the electric charge. An electrostatic field comes about from charges at rest, and the magnetic field comes about from charges in motion. And since motion and rest are merely matters of opinion, who is to say which is which?"
Electromagnetism"[T]here does not seem to be definite experimental evidence to indicate that the electronic mass is entirely electromagnetic."
Electromagnetism"The third closed system of concepts and axioms has its origin in the phenomena of electricity and magnetism and has reached its final form in the first decade of the twentieth century through the work of Lorentz, Einstein and Minkowski. It comprises electrodynamics, special relativity, optics, magnetism, and one may include the de Broglie theory of matter waves of all different sorts of elementary particles, but not the wave theory of Schrodinger."
Electromagnetism"The color gauge theory postulates the existence of eight massless particles, sometimes called s, that are the carriers of the just as the photon is the carrier of the electromagnetic force."
Electromagnetism"In 1933 Enrico Fermi suggested that beta radioactivity, and the manner in which the neutron spontaneously decayed, could be described using a formalsm similar to that developed by Dirac for the electromagnetic force, but 10-10 times weaker. With its range of only about 1/1,000th the diameter of the nucleus, it could not play a role in binding the nucleus, but it could affect individual s. The fact that the metastable particles exhibited the same characteristic time of 10-10 second indicated that this weak force acted on many types of particles. ...a characteristic time ...being the time for an interaction across a nucleus 3 fm in diameter; an event taking place in a shorter time [than 10-23 seconds for the strong force] has no meaning. ...For electromagnetic interactions, the strength is 10-3 of the strong force, and so the characteristic time is longer (10-20 [seconds]); this is roughly the time for a photon to cross an atom."
Electromagnetism"Einstein[s] results concerning electromagnetic and optical phenomena ...agree in the main with those which we have obtained... the chief difference being that Einstein simply postulates what we have deduced, with some difficulty and not altogether satisfactorily, from the fundamental equations of the electromagnetic field. By doing so, he may certainly take credit for making us see in the negative result of experiments like those of Michelson, Rayleigh and Brace, not a fortuitous compensation of opposing effects, but the manifestation of a general and fundamental principle. Yet, I think, something may also be claimed in favour of the form in which I have presented the theory. I cannot but regard the ether, which can be the seat of an electromagnetic field with its energy and vibrations, as endowed with a certain degree of substantiality, however different it may be from all ordinary matter. ...it seems natural not to assume at starting that it can never make any difference whether a body moves through the ether or not, and to measure distances and lengths of time by means of rods and clocks having a fixed position relatively to the ether. It would be unjust not to add that, besides the fascinating boldness of its starting point, Einsteins theory has another marked advantage over mine. ..."
Electromagnetism