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Diagram regarding the confirmation of gravitomagnetism by Gravity Probe B. Gravitoelectromagnetism, abbreviated GEM, refers to a set of formal analogies between the equations for electromagnetism and relativistic gravitation; specifically: between Maxwell's field equations and an approximation, valid under certain conditions, to the Einstein field equations for general relativity.
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 phenomena. Electromagnetic forces occur between any two charged particles.
The gravitational and electromagnetic interactions produce long-range forces whose effects can be seen directly in everyday life. The strong and weak interactions produce forces at subatomic scales and govern nuclear interactions inside atoms. Some scientists hypothesize that a fifth force might exist, but these hypotheses remain speculative.
Analogously, Coulomb's law is the fundamental law that describes the force that charged objects exert on one another. It is given by the formula = where F is the force, k e is the Coulomb constant, q 1 and q 2 are the magnitudes of the two charges, and r 2 is the square of the distance between them. It describes the fact that like charges repel ...
Lorentz force on a charged particle (of charge q) in motion (velocity v), used as the definition of the E field and B field. Here subscripts e and m are used to differ between electric and magnetic charges. The definitions for monopoles are of theoretical interest, although real magnetic dipoles can be described using pole strengths.
A changing electromagnetic field which is physically close to currents and charges (see near and far field for a definition of "close") will have a dipole characteristic that is dominated by either a changing electric dipole, or a changing magnetic dipole. This type of dipole field near sources is called an electromagnetic near-field.
[36] [37]: 35 The electromagnetic force is very strong, second only in strength to the strong interaction, [38] but unlike that force it operates over all distances. [39] In comparison with the much weaker gravitational force , the electromagnetic force pushing two electrons apart is 10 42 times that of the gravitational attraction pulling them ...
The gravitational field of M at a point r in space is found by determining the force F that M exerts on a small test mass m located at r, and then dividing by m: [1] = (). Stipulating that m is much smaller than M ensures that the presence of m has a negligible influence on the behavior of M .