Keywords
CGS-EMU
International System
Magnetic Fields
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Abstract
Even though the International System of Units (SI) is the official standard, the CGS-EMU system is still commonly used in the field of magnetism. The coexistence of both systems of units generates confusion and errors, both for students and researchers. In this article we try to describe the history and evolution of these systems, to understand this controversial coexistence. Emphasis is placed on magnetic units and conversion factors between both systems.
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El CGS se subdividió en dos subsistemas: CGS-EMU (preferido en estudios electromagnéticos y materiales magnéticos) y CGS-ESU (usado históri-camente para cálculos de electrostática). Las uni-dades eléctricas del sistema EMU contienen al pre-fijo “ab”, de absoluto –abamperio (o Biot), abVoltio, abCulombio, etc.– mientras que las del ESU conlle-van el prefijo “estat”, de estático –estatamperio (o Franklin), estatVoltio, etc.–. El factor de conversión entre esta unidades es el valor de la velocidad de la luz, c ≈ 3·1010 cm/s, por lo que son unidades con varios órdenes de magnitud diferente: 1 abA = c·1 estatA, 1 abV = (1/c)·1 estatV, 1 abC = c·1 estatC, etc. Su conversión al SI es: 1 abA = 10 A, 1 abV = 10-8 V, 1 abC = 10 C.
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