Before the introduction of the international system of units SI, the following systems of units were used.
Metric- set of units physical quantities, which is based on two units: a meter is a unit of length, a kilogram is a unit of mass. Distinctive feature The metric system of measures was the principle of decimal ratios in relation to multiples and submultiples. Metric, originally introduced in France, received in the second half of the 19th century. international recognition.
The concept of a system of units of physical quantities was first introduced by the German mathematician K. Gauss (1832). Gauss' idea was as follows. First, several values are selected that are independent of each other. These quantities are called basic, and their units are called basic units. systems of units. The basic quantities are chosen so that, using formulas expressing the relationship between physical quantities, it is possible to form units of other quantities. Units obtained with the help of formulas and expressed in terms of basic units, Gauss called derived units. Using his idea, Gauss built unit system magnetic quantities. The basic units of this Gaussian system were chosen: millimeter - a unit of length, second - a unit of time. Gauss's ideas turned out to be very fruitful. All subsequent systems of units based on the principles they proposed.
GHS system built on the basis of the system of LMT values. The basic units of the CGS system: centimeter - a unit of length, gram - a unit of mass, second - a unit of time. In the CGS system, using these three basic units, derived units of mechanical and acoustic quantities are established. Using the unit of thermodynamic temperature - kelvin - and the unit of luminous intensity - candela - the CGS system extends to the region of thermal and optical quantities.
Basic units ISS systems: meter is a unit of length, kilogram is a unit of mass, second is a unit of time. Like the CGS system, the ISS system is based on the LMT system. This system of units was proposed in 1901 by the Italian engineer Giorgi and contained, in addition to the basic derivative units of mechanical and acoustic quantities. By adding thermodynamic temperature, the kelvin, and luminous intensity, the candela, as basic units, the ISS system could be extended to the region of thermal and light quantities.
MTS system of units built on the basis of the system of LMT values. The main units of the system: meter - a unit of length, ton - a unit of mass, second - a unit of time. The MTS system was developed in France and legalized by its government in 1919. The MTS system was also adopted in the USSR and was used in accordance with the state standard for more than 20 years (1933 - 1955). The unit of mass of this system, the ton, proved to be convenient in its size in a number of industries dealing with relatively large masses. The MTS system also had a number of other advantages. Firstly, the numerical values of the density of a substance when expressed in the MTS system coincided with the numerical values of this value when expressed in the CGS system (for example, in the CGS system, the density of iron is 7.8 g / cm3, in the MTS system - 7.8 t / m3 ). Secondly, the unit of work of the MTS system - kilojoule - had a simple relationship with the unit of work of the ISS system (1 kJ = 1000 J). But the sizes of the units of the overwhelming majority of derived quantities in this system turned out to be inconvenient in practice. In the USSR, the MTS system was abolished in 1955.
MKGSS system of units is built on the basis of the system of LFT values. Its basic units are: meter - a unit of length, kilogram-force - a unit of force, second - a unit of time. Kilogram-force - a force equal to the weight of a body with a mass of 1 kg at normal free fall acceleration g0 = 9.80665 m/s2. This unit of force, as well as some derived units of the MKGSS system, turned out to be convenient for their application in technology. Therefore, the system has become widespread in mechanics, heat engineering and a number of other industries. The main disadvantage of the MKGSS system is its very limited possibilities of application in physics. A significant drawback of the MKGSS system is also that the unit of mass in this system does not have a simple decimal relationship with the mass units of other systems. With an introduction international system units, the ICSC system has lost its significance.
Systems of units of electromagnetic quantities. There are two ways to build systems of electrical and magnetic quantities based on the CGS system: on three basic units (centimeter, gram, second) and on four basic units (centimeter, gram, second and one unit of electrical or magnetic quantity). In the first way, that is, using three basic units based on the CGS system, three systems of units were obtained: the electrostatic system of units (CGSE system), the electromagnetic system of units (CGSM system), the symmetrical system of units (CGS system). Let's take a look at these systems.
Electrostatic system of units (CSSE system). When constructing this system, the unit of electric charge is introduced by the first derivative of the electrical unit using Coulomb's law as the defining equation. In this case, the absolute permittivity is considered as a dimensionless electrical quantity. As a consequence of this, in some equations relating electromagnetic quantities, the square root of the speed of light in vacuum appears in an explicit form.
Electromagnetic system of units (SGSM system). When constructing this system, the unit of current strength is introduced by the first derivative of the electrical unit using Ampère's law as a defining equation. In this case, the absolute magnetic permeability is considered as a dimensionless electrical quantity. In this regard, in some equations relating electromagnetic quantities, the square root of the speed of light in vacuum appears in an explicit form.
Symmetric system of units (CGS system). This system is a combination of SGSE and SGSM systems. In the CGS system, units of the CGSE system are used as units of electrical quantities, and units of the CGSM system are used as units of magnetic quantities. As a result of the combination of the two systems, in some equations relating electrical and magnetic quantities, the square root of the speed of light in vacuum appears in an explicit form.
; adopted by the 1st Intern. Congress of Electricians (Paris, 1881) as a system of units covering mechanics and electrodynamics. For electrodynamics, two CGS s were originally adopted. e.: el.-mag. (SGSM) and electrostatic (SGSE). The basis for the construction of these systems was Coulomb's law of influence of electric. charges (SGSE) and magnetic. charges (SGSM). In SGSM with. e. magn. vacuum permeability (magnetic constant) m0=1, and electric. vacuum permeability (electrical constant) e0=1/s2 s2/cm2, where s - . The CGSM unit of the magnetic flux is yavl. (Mks, Mx), magnetic induction - (Gs, Gs), magnetic strength. fields - (E, Oe), magnetomotive force - (Gb, Gb). Electric units in this system own. no names assigned. In SGSE with. e. e0=1, m0=l/c2 s2/cm2. Electric units SGSE own. do not have names; their size, as a rule, is inconvenient for measurements; apply them. arr. in theor. works.
From the 2nd floor. 20th century the most widespread was the so-called. symmetrical GHS s. e. (it is also called the mixed or Gaussian system of units). In the symmetric CGS with. e. m0=1 and e0=1. Magn. the units of this system are equal to the units of the CGSM, and the electrical units are equal to the units of the CGSE system.
Based on GHS s. That is, a system of thermal units CGS °C (cm - g - s - ° C), light units SGSL (cm - g - s - ) and units of radioactivity and ionizing radiation SGSR (cm - g - s - ) were also created. Application of the GHS p. e. is allowed in theory. works in physics and astronomy.
The ratios of the most important units of the three above CGS systems and the corresponding SI units are given in the table.
Physical encyclopedic Dictionary. - M.: Soviet Encyclopedia. . 1983
GHS SYSTEM OF UNITS
The system of physical units. values from the main units: centimeter, gram, second (CGS); accepted 1st International congress electricians (Paris, 1881) as a system of units covering mechanics and electrodynamics. Coulomb's law of interaction of electric. charges (SGSE) and magnetic. In the CGSM system of units, magn. vacuum permeability ( magnetic constant), and electric vacuum permeability ( electrical constant); unit of magn. flow is maxwell (Mx, Mx), magn. induction - gauss(Gs, Gs), magnetic strengths. fields - oersted (E, Oe), magnetomotive force - Gilbert (Gb, Gb). Electric units in this system own. names not assigned.
In the GSSE system,. Electric From the 2nd floor. 20th century max. the so-called Gaussian system of units, the mixed system of units, became widespread). In it and; magn. Application of the GHS p. e. is allowed in scientific. research. The ratio of the most important units of the CGS system and the corresponding SI units are given in Table. 
Lit.: Sena L. A., Units of physical quantities and their dimensions, 3rd ed., M., 1989.
Physical encyclopedia. In 5 volumes. - M.: Soviet Encyclopedia. Editor-in-Chief A. M. Prokhorov. 1988 .
- (SGS), a system of units of physical quantities with 3 basic units: length centimeter; mass grams; time second. It is mainly used in physics and astronomy. In electrodynamics, two CGS systems of units were used: electromagnetic ... ... encyclopedic Dictionary
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cgs system of units- (SGS), a system of units of physical quantities with basic units: cm g (mass) s. In electrodynamics, two CGS systems of units were used - electromagnetic (CGSM) and electrostatic (CGSE), as well as a mixed one (the so-called Gaussian system of units) ... Illustrated Encyclopedic Dictionary
cgs system of units- CGS vienetų sistema statusas T sritis Kūno kultūra ir sportas apibrėžtis Absoliuti fizikinių dydžių vienetų sistema, kurios pagrindiniai vienetai yra centimetras (cm), gramas (g) ir sekundė (s). atitikmenys: engl. CGS system vok. ZGS System, n… … Sporto terminų žodynas
CGS (centimeter gram second) is a system of units that was widely used before the adoption of the International System of Units (SI). Within the CGS, there are three independent dimensions (length, mass and time), all the rest are reduced to them by ... ... Wikipedia
The system of units of physical quantities, in which three basic units are accepted: length, centimeter, mass, grams, and time, second. A system with basic units of length, mass, and time was proposed by the Committee on Electricity, formed in 1861. Big soviet encyclopedia
- (SGS), system of physical units. values from 3 main. units: length centimeter; mass grams; time second. Applies Ch. arr. in physics and astronomy. In electrodynamics, two CGSs were used. e.: el. magn. (SGSM) and email. static (SGSE). In the 20th century ... ... Natural science. encyclopedic Dictionary
The system of units of physical quantities with basic units: cm g (mass) s. It is mainly used in works on physics and astronomy. Two systems of CGS units were used in electrodynamics: electromagnetic (CGSM) and electrostatic (CGSE). AT… … Big Encyclopedic Dictionary
Physical quantities, a set of basic and derived units of a certain system of physical. quantities, formed in accordance with accepted principles. S. e. is built on the basis of physical. theories reflecting the interrelation existing in the nature physical. quantities. At … Physical Encyclopedia
A set of basic (independent) and derived units of physical quantities, reflecting the interrelations of these quantities existing in nature. When determining the units of the system, such a sequence of physical relationships is selected in which each ... ... encyclopedic Dictionary
CGS (centimeter-gram-second)- a system of units of measurement that was widely used before the adoption of the International System of Units (SI). Another name is the absolute physical system of units.
Within the framework of the CGS, there are three independent dimensions (length, mass and time), all the rest are reduced to them by multiplication, division and exponentiation (possibly fractional). In addition to the three basic units of measurement - centimeter, gram and second, in the CGS there are a number of additional units of measurement that are derived from the main ones. Some physical constants become dimensionless. There are several variants of the CGS, which differ in the choice of electrical and magnetic units of measurement and the magnitude of the constants in various laws of electromagnetism (CGSE, CGSM, Gaussian system of units). The GHS differs from the SI not only in the choice of specific units of measurement. Due to the fact that the basic units for electromagnetic physical quantities were additionally introduced into the SI, which were not in the CGS, some units have other dimensions. Because of this, some physical laws in these systems are written differently (for example, Coulomb's law). The difference lies in the coefficients, most of which are dimensional. Therefore, if you simply substitute SI units in the formulas written in the CGS, then incorrect results will be obtained. The same applies to different varieties CGS - in CGSE, CGSM and Gaussian units, the same formulas can be written in different ways.
The CGS formulas lack non-physical coefficients required in SI (for example, the electrical constant in Coulomb's law), and, in the Gaussian version, all four vectors of electric and magnetic fields E, D, B and H have the same dimensions, in accordance with their physical meaning , therefore, the CGS is considered more convenient for theoretical studies.
AT scientific papers, as a rule, the choice of a particular system is determined by more continuity of designations and transparency physical sense than the convenience of measurements.
A system of measures based on the centimeter, gram and second was proposed by the German scientist Gauss in 1832. In 1874 Maxwell and Thomson improved the system by adding electromagnetic units of measurement to it.
The values of many units of the CGS system were found to be inconvenient for practical use, and it was soon replaced by a system based on the meter, kilogram and second (MKS). GHS continued to be used in parallel with the ISS, mainly in scientific research.
After the adoption of the SI system in 1960, the CGS almost fell out of use in engineering applications, but continues to be widely used, for example, in theoretical physics and astrophysics due to more simple form laws of electromagnetism.
Of the three additional systems The most widely used CGS system is symmetrical.
The table lists the names conventions and dimensions of the most commonly used units in the SI system. For the transition to other systems - CGSE and SGSM - the last columns show the ratios between the units of these systems and the corresponding units of the SI system.
For mechanical quantities, the CGSE and CGSM systems completely coincide, the main units here are the centimeter, gram and second.
The difference in CGS systems takes place for electrical quantities. This is due to the fact that the electrical permeability of the void (ε 0 =1) is taken as the fourth basic unit in the CGSE, and the magnetic permeability of the void (μ 0 =1) in the SGSM.
In the Gaussian system, the basic units are centimeter, gram and second, ε 0 =1 and μ 0 =1 (for vacuum). In this system electrical quantities are measured in CGSE, magnetic - in CGSM.
| Value | Name | Dimension | Symbol | Contains units GHS systems |
|
| SGSE | SGSM | ||||
| Basic units | |||||
| Length | meter | m | m | 10 2 cm | |
| Weight | kilogram | kg | kg | 10 3 g | |
| Time | second | sec | sec | 1sec | |
| Current strength | ampere | AND | AND | 3×10 9 | 10 -1 |
| Temperature | Kelvin | To | To | - | - |
| degree Celsius | °C | °C | - | - | |
| The power of light | candela | cd | cd | - | - |
| Mechanical units | |||||
| Quantity electricity |
pendant | cl | 3×10 9 | 10 -1 | |
| Voltage, EMF | volt | AT | 10 8 | ||
| tension electric field |
volt per meter | 10 8 | |||
| Electrical capacity | farad | 
|
F | 9×10 11 cm | 10 -9 |
| Electrical resistance |
ohm | Ohm | 10 9 | ||
| specific resistance |
ohm meter | 
|
10 11 | ||
| Dielectric permeability |
farad per meter | ||||
| Magnetic units | |||||
| tension magnetic field |
ampere per meter | ||||
| Magnetic induction |
tesla | Tl | 10 4 Gs | ||
| magnetic flux | weber | wb | 10 8 ms | ||
| Inductance | Henry | 
|
gn | 10 8 cm | |
| Magnetic permeability |
henry per meter | ||||
| Optical units | |||||
| Solid angle | steradian | erased | erased | - | - |
| Light flow | lumen | lm | - | - | |
| Brightness | nit | nt | - | - | |
| illumination | luxury | OK | - | - | |
Some definitions
The strength of the electric current- the strength of an unchanging current, which, passing through two parallel rectilinear conductors of infinite length and negligible cross-section, located at a distance of 1 m from one another in a vacuum, would cause a force between these conductors equal to 2 × 10 -7 N for each meter of length.
Kelvin- a temperature unit equal to 1/273 of the interval from absolute zero temperatures to the temperature of melting ice.
Candela(candle) - the intensity of light emitted from an area of \u200b\u200b1/600000m 2 of the cross section of a full emitter, in a direction perpendicular to this section, at an emitter temperature equal to the solidification temperature of platinum at a pressure of 1011325Pa.
newton- the force that imparts an acceleration of 1 m / s 2 to a body with a mass of 1 kg in the direction of its action.
Pascal- pressure caused by a force of 1N, evenly distributed over a surface area of 1m 2.
Joule- the work of the force 1N when it moves the body at a distance of 1m in the direction of its action.
Watt is the power at which 1J of work is done in 1 second.
Pendant is the amount of electricity passing through cross section conductor for 1 second at a current of 1A.
Volt- tension in the area electrical circuit with a constant current of 1A, in which a power of 1W is expended.
Volt per meter- the intensity of a homogeneous electric field, at which a potential difference of 1V is created between points located at a distance of 1 m along the field strength line.
Ohm- the resistance of the conductor, between the ends of which, at a current strength of 1A, a voltage of 1V appears.
ohm meter- electrical resistance of the conductor, at which the cylindrical straight conductor with a cross section of 1m 2 and a length of 1m has a resistance of 1 ohm.
Farad- the capacitance of the capacitor, between the plates of which, when charging 1C, a voltage of 1V appears.
Amp per meter- magnetic field strength in the center of a long solenoid with n turns per meter of length, through which a current of strength A / n passes.
Weber- a magnetic flux, when it decreases to zero in a circuit linked to this flux, with a resistance of 1 Ohm, an amount of electricity 1 Kl passes.
Henry- the inductance of the circuit, with which, with a direct current of 1A, a magnetic flux of 1Wb is coupled in it.
Tesla- magnetic induction, at which the magnetic flux through a cross section of 1m 2 is equal to 1Wb.
Henry per meter- absolute magnetic permeability of the medium in which, at a magnetic field strength of 1A/m, a magnetic induction of 1H is created.
Steradian- solid angle, the vertex of which is located in the center of the sphere and which cuts out an area on the surface of the sphere, equal to the area a square with a side equal to the radius of the sphere.
Lumen- the product of the luminous intensity of the source and the solid angle into which the luminous flux is sent.
Some off-system units
| Value | unit of measurement | Value in SI units |
|
| Name | designation | ||
| Force | kilogram-force of walls | sn | 10N |
| pressure and mechanical voltage |
technical atmosphere | at | 98066.5Pa |
| kilogram-force square centimeter |
kgf / cm 2 | ||
| physical atmosphere | atm | 101325Pa | |
| millimeter of water column | mm w.c. Art. | 9.80665Pa | |
| millimeter of mercury | mmHg Art. | 133.322Pa | |
| Work and energy | kilogram-force-meter | kgf×m | 9.80665J |
| kilowatt-hour | kWh | 3.6×10 6 J | |
| Power | kilogram-force-meter per second |
kgf×m/s | 9.80665W |
| Horsepower | hp | 735.499W | |
Interesting fact. The concept of horsepower was introduced by the father famous physicist Watt. Watt's father was a steam engine designer, and it was vital for him to convince the mine owners to buy his machines instead of draft horses. So that the owners of the mines could calculate the benefits, Watt coined the term horsepower to determine the power of steam engines. One HP according to Watt, this is 500 pounds of cargo that a horse could pull all day. So one horsepower is the ability to pull a cart with 227kg of cargo during a 12 hour working day. The steam engines sold by Watt had only a few horsepower.
Prefixes and multipliers for the formation of decimal multiples and submultiples
| Prefix | Designation | The multiplier for which units are multiplied SI systems |
|
| domestic | international | ||
| Mega | M | M | 10 6 |
| Kilo | to | k | 10 3 |
| Hecto | G | h | 10 2 |
| Deca | Yes | da | 10 |
| Deci | d | d | 10 -1 |
| Santi | With | c | 10 -2 |
| Milli | m | m | 10 -3 |
| Micro | mk | µ | 10 -6 |
| Nano | n | n | 10 -9 |
| Pico | P | p | 10 -12 |
There are a number of additional units of measurement in the GHS, which are derived from the main ones. Some physical constants turn out to be dimensionless. There are several variants of the CGS, which differ in the choice of electrical and magnetic units of measurement and the magnitude of the constants in various laws of electromagnetism (CGSE, CGSM, Gaussian system of units).
The GHS differs from the SI not only in the choice of specific units of measurement. Due to the fact that the basic units for electromagnetic physical quantities were additionally introduced into the SI, which were not in the CGS, some units have other dimensions. Because of this, some physical laws in these systems are written differently (for example, Coulomb's law). The difference lies in the coefficients, most of which are dimensional. Therefore, if you simply substitute SI units in the formulas written in the CGS, then incorrect results will be obtained. The same applies to different varieties of CGS - in the CGSE, CGSM and Gaussian system of units, the same formulas can be written in different ways.
The CGS formulas lack the non-physical coefficients required in the SI (for example, the electric constant in Coulomb's law), so it is considered more convenient for theoretical studies.
In scientific works, as a rule, the choice of one or another system is determined more by the continuity of designations, and not by convenience.
To facilitate work in the CGS in electrodynamics, the CGSM and CGSE systems were additionally adopted.
In the CGSE µ 0 = 1/ With 2 (dimension: s 2 / cm 2), ε 0 = 1. Electrical units in the CGSE system are used mainly in theoretical works. They do not have their own names and are inconvenient for measurements.
In the symmetric CGS (also called the mixed CGS or Gaussian system of units), magnetic units are equal to units of the CGSM system, electrical units are equal to the units of the CGSE system. The magnetic and electric constants in this system are single and dimensionless: µ 0 = 1, ε 0 = 1.
A system of measures based on the centimeter, gram and second was proposed by the German scientist Gauss in. Maxwell and Thomson improved the system by adding electromagnetic units of measurement to it.
The values of many units of the CGS system were found to be inconvenient for practical use, and it was soon replaced by a system based on the meter, kilogram and second (MKS). GHS continued to be used in parallel with the ISS, mainly in scientific research.
Of the three additional systems, the symmetrical CGS system is the most widely used.
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