CGS system of units - CGS system of units

Japanese: CGS単位系 - しーじーえすたんいけい（英語表記）C.G.S. system of units

A system of units with centimeters (cm) for length, grams (g) for mass, and seconds (s) for time as base units. When temperature is added, Celsius temperature (℃) is used. It was internationally decided in 1881 and has been used for a long time in the field of physics. However, since the units are too small for practical use and the relationship with practical electrical units is complicated, the MKS system or the MKSA system, which adds the absolute ampere as a base unit, is often used. Furthermore, with the establishment of the International System of Units (SI) in 1960, the SI system has come to be used as the basic unit.

[Koizumi Kesakatsu and Imai Hidetaka]

CGS electrostatic units

A system of units that adds a unit of electric charge determined using Coulomb's law for static electricity as a base unit to the CGS system of units. It is also written as CGSesu, where esu is an abbreviation of electrostatic unit. In expressing the Coulomb force acting between two charges, the unit of electric charge is defined without giving dimensions to the dielectric constant of the medium.

[Koizumi Kesakatsu]

CGS Electromagnetic Unit System

A system of units that adds units of electromagnetic quantities determined using Coulomb's law for magnetism to the CGS system. Also written as CGSemu, emu is an abbreviation of electromagnetic unit. It is the Coulomb force acting between two magnetic charges, and it is defined that the magnetic permeability of a medium has no dimension, in other words, that the magnetic charge has the same dimension as the electric charge.

[Koizumi Kesakatsu]

[Reference] | MKS Unit System | Coulomb's Law | Dimensions | Units

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

基本単位として長さにセンチメートル（cm）、質量にグラム（g）、時間に秒（s）をとった単位系。温度が加わる場合には摂氏温度（セルシウス温度）℃が用いられる。1881年に国際的に決められ、物理学の分野で長く使用されてきた。しかし、実用的には単位が小さすぎ、電気の実用単位との関係も複雑になるため、MKS単位系や絶対アンペアを基本単位に加えたMKSA単位系を用いることが多い。さらに、1960年の国際単位系（SI）の制定により、基本的にSIが用いられるようになった。

［小泉袈裟勝・今井秀孝］

CGS静電単位系

CGS単位系に、静電気に関するクーロンの法則を利用して定めた電気量の単位を基本単位として加えた単位系。C.G.S.esuとも記し、esuはelectrostatic unit（静電単位）の略。二つの電荷の間に働くクーロンの力の表現において、媒質の誘電率に次元をもたせないようにして電気量の単位を定義している。

［小泉袈裟勝］