The electrostatic system of units (CGS-ESU) is a system of units used to measure quantities of
electric charge
Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons respe ...
,
electric current, and
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...
within the
centimetre–gram–second (or "CGS") system of metric units. In electrostatic units, electrical charge is defined by the force that it exerts on other charges.
Although CGS units have mostly been replaced by the ''
International System of Units'', electrostatic units are still in occasional use in some applications, most notably in certain types of physics such as in
particle physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...
and
astrophysics.
The main electrostatic units are:
*The
statcoulomb
The franklin (Fr) or statcoulomb (statC) electrostatic unit of charge (esu) is the physical unit for electrical charge used in the cgs-esu and Gaussian units. It is a derived unit given by
: 1 statC = 1 dyn1/2⋅cm = 1 cm3/2⋅g1/2⋅s−1.
Tha ...
, called the
franklin or the "esu" for
electric charge
Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons respe ...
*The
statvolt for
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...
*The
statampere for
electric current.
The CGS-ESU units for magnetic quantities are seldom used,
and don't have special names. Sources tend to just use 'esu' or the derived unit expressed in terms of the CGS base units. For example, the unit for magnetic induction is g/cm, corresponding to
gauss
Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...
, and corresponding to ×, where = /(cm/s) = is the numeric part of
speed of light
The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit ...
expressed in CGS units.
See also
*
References
External links
Electrical units
{{CGS units
Centimetre–gram–second system of units
Electricity