Whereas gravity acts on all things that have mass, electromagnetism acts on all things that have electric charge. Quantum considerations are also necessary to explain the behaviour of many electronic devices, for instance the tunnel diode.Ĭoulomb's law tells us that like charges repel and opposite charges attract.Įlectromagnetism is one of the fundamental forces of nature alongside gravity, the strong force and the weak force. Chemical reactions and chemical bonding are the result of quantum mechanical interactions of electrons around atoms. On the other hand, a quantum treatment of electromagnetism is important in chemistry. In such circuits, even Maxwell's equations can be dispensed with and simpler formulations used. Circuit theory deals with electrical networks where the fields are largely confined around current carrying conductors. Permanent magnets can be described without reference to electricity or electromagnetism. Electrostatics deals only with stationary electric charges so magnetic fields do not arise and are not considered. Further simplifications of treatment are possible in limited situations. With few exceptions, quantum theory is only necessary at the atomic scale and a simpler classical treatment can be applied. Classical physics is still an accurate approximation in most situations involving macroscopic objects. In many situations of interest to electrical engineering, it is not necessary to apply quantum theory to get correct results. The modern theoretical treatment of electromagnetism is as a quantum field in quantum electrodynamics. 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. Radio waves differ from light only in that the wavelength of the former is much longer than the latter. Maxwell also postulated, correctly, that light was a form of electromagnetic wave, thus making all of optics a branch of electromagnetism. Maxwell's equations further indicated that electromagnetic waves existed, and the experiments of Heinrich Hertz confirmed this, making radio possible. 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. Hans Christian Ørsted discovered that the two were related – electric currents give rise to magnetism. Early on, electricity and magnetism were studied separately and regarded as separate phenomena. For a more detailed mathematical treatment, see electromagnetic field.Įlectromagnetism is one of the fundamental forces of nature. ![]() This article is about a conceptual understanding of the topic.
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