Introduction to electromagnetism

rdf:langString Introduction to electromagnetism

rdf:langString If there is no charge enclosed by a closed surface, then the amount of electric field flowing into it must exactly cancel with the electric field flowing out of it.

rdf:langString Because the flow of magnetic field out of a closed surface must cancel with the flow into it, magnets must have both North and South poles which cannot be separated into monopoles.

rdf:langString The electron's rest frame

rdf:langString The lab frame

rdf:langString Kirchoff's junction rule : I1 + I2 + I3 = I4 + I5 Kirchoff's loop rule : V1 + V2 + V3 + V4 = 0

rdf:langString vertical

rdf:langString The right-hand grip rule for a straight wire and for a coiled wire . Electrical current passed through a wire coiled around an iron core can produce an electromagnet.

rdf:langString The force exerted on a positive charge by an electric field and a magnetic field combine to give the Lorentz force.

rdf:langString Coil right-hand rule.svg

rdf:langString GaussLaw2.svg

rdf:langString KVL.png

rdf:langString Manoderecha.svg

rdf:langString Pierwsze prawo Kirchhoffa.svg

rdf:langString Relativistic electromagnetism fig5.svg

rdf:langString Relativistic electromagnetism fig6.svg

rdf:langString VFPt Earths Magnetic Field Confusion.svg

rdf:langString Openstax college-physics 22.17 Lorentz-force-right-hand.jpg

rdf:langString Force of an electric field on a positive charge.png

rdf:langString Electromagnetism is one of the fundamental forces of nature. Early on, electricity and magnetism were studied separately and regarded as separate phenomena. Hans Christian Ørsted discovered that the two were related – electric currents give rise to magnetism. Michael Faraday discovered the converse, that magnetism could induce electric currents, and James Clerk Maxwell put the whole thing together in a unified theory of electromagnetism. Maxwell's equations further indicated that electromagnetic waves existed, and the experiments of Heinrich Hertz confirmed this, making radio possible. Maxwell also postulated, correctly, that light was a form of electromagnetic wave, thus making all of optics a branch of electromagnetism. Radio waves differ from light only in that the wavelength of the former is much longer than the latter. Albert Einstein showed that the magnetic field arises through the relativistic motion of the electric field and thus magnetism is merely a side effect of electricity. The modern theoretical treatment of electromagnetism is as a quantum field in quantum electrodynamics. In many situations of interest to electrical engineering, it is not necessary to apply quantum theory to get correct results. Classical physics is still an accurate approximation in most situations involving macroscopic objects. With few exceptions, quantum theory is only necessary at the atomic scale and a simpler classical treatment can be applied. Further simplifications of treatment are possible in limited situations. Electrostatics deals only with stationary electric charges so magnetic fields do not arise and are not considered. Permanent magnets can be described without reference to electricity or electromagnetism. Circuit theory deals with electrical networks where the fields are largely confined around current carrying conductors. In such circuits, even Maxwell's equations can be dispensed with and simpler formulations used. On the other hand, a quantum treatment of electromagnetism is important in chemistry. Chemical reactions and chemical bonding are the result of quantum mechanical interactions of electrons around atoms. Quantum considerations are also necessary to explain the behaviour of many electronic devices, for instance the tunnel diode.