Emu Codes -

| EMU unit | Symbol | Quantity | SI equivalent | |----------|--------|----------|----------------| | abampere | aA | current | 10 A | | abvolt | aV | potential | 10⁻⁸ V | | gauss | G | magnetic flux density | 10⁻⁴ T | | oersted | Oe | magnetic field strength | (1000/(4π)) ≈ 79.577 A/m | | maxwell | Mx | magnetic flux | 10⁻⁸ Wb | | gilbert | Gb | magnetomotive force | (10/(4π)) ≈ 0.7958 A-t |

Abstract EMU codes, derived from the electromagnetic unit system (part of the CGS framework), represent a set of standardized symbolic identifiers used to specify electromagnetic quantities, conversion factors, and measurement protocols. While largely superseded by SI units in mainstream science and engineering, EMU codes persist in specialized domains such as low-temperature physics, magnetometry, and archival technical documentation. This paper examines the origin, logical structure, practical applications, and limitations of EMU codes, offering a guide for their interpretation and interconversion with modern SI-based systems. 1. Introduction The centimeter-gram-second (CGS) system historically included several subsystems for electromagnetism, among which the Electromagnetic Units (EMU) system was prominent. EMU codes refer to alphanumeric or symbolic labels assigned to specific electromagnetic quantities (e.g., abampere, abvolt, gauss, oersted) to facilitate compact notation, data recording, and instrument calibration. Although not a formal “code” in the cryptographic sense, EMU codes function as shorthand identifiers in technical tables, legacy equipment manuals, and scientific software. emu codes

This paper addresses three core questions: (1) What is the structural logic of EMU codes? (2) Where are they still encountered? (3) How can one convert EMU-based values to SI reliably? The EMU system defines electromagnetic units in terms of the centimeter, gram, and second, with the magnetic constant ( \mu_0 ) set to ( 1 ) (dimensionless). This yields coherent units that differ from SI by powers of 10 or more complex factors. Key EMU units include: | EMU unit | Symbol | Quantity |