Since 1963 in the USSR (GOST 9867-61 "International System of Units"), in order to unify units of measurement in all fields of science and technology, the international (international) system of units (SI, SI) is recommended for practical use. , adopted by the XI General Conference on Measures and Weights in 1960. It is based on 6 basic units (length, mass, time, electric current, thermodynamic temperature and luminous intensity), as well as 2 additional units (flat angle, solid angle) ; all other units listed in the table are their derivatives. The adoption of a single international system of units for all countries is intended to eliminate the difficulties associated with the translation of the numerical values of physical quantities, as well as various constants from any one of the current systems (GHS, ICSCS, ISS A, etc.), another one.

Name of the value | Units; SI values | Legend | |
---|---|---|---|

Russian | inter-national | ||

I. Length, mass, volume, pressure, temperature
| |||

Length | Meter - a measure of length, numerically equal to the length of the international standard meter; 1 m = 100 cm (1 · 10 ^{2} cm) = 1000 mm (1 · 10 ^{3} mm) | m | m |

Centimeter = 0.01 m (1 · 10 ^{-2} m) = 10 mm | cm | cm | |

Millimeter = 0.001 m (1 · 10 ^{-3} m) = 0.1 cm = 1000 microns (1 · 10 ^{3} microns) | mm | mm | |

Micron (micrometer) = 0.001 mm (1 · 10 ^{-3} mm) = 0, 0001 cm (1 · 10 ^{-4} cm) = 10 000 | micron | μ | |

Angstrom = one ten-billionth meter (1 · 10 ^{-10} m) or one hundred-millionth centimeter (1 · 10 ^{-8} cm) | Å | Å | |

Weight | A kilogram is the basic unit of mass in the metric system of measures and the SI system, numerically equal to the mass of the international standard of the kilogram; 1 kg = 1000 g | kg | kg |

Gram = 0.001 kg (1 · 10 ^{-3} kg) | g | g | |

Ton = 1000 kg (1 · 10 ^{3} kg) | t | t | |

Centner = 100 kg (1 · 10 ^{2} kg) | c | ||

Carat is a non-system mass unit, numerically equal to 0.2 g | ct | ||

Gamma = one millionth gram (1 · 10 ^{-6} g) | γ | ||

Volume | Liter = 1,000028 dm ^{3} = 1,000028 · 10 ^{-3} m ^{3} | l | l |

Pressure | Physical or normal atmosphere - pressure balanced by a mercury column with a height of 760 mm at a temperature of 0 ° = 1.033 at = = 1.01 · 10 ^{-5} N / m ^{2} = 1.01325 bar = 760 Torr = 1, 033 kgf / cm ^{2} | atm | atm |

Technical atmosphere - pressure equal to 1 kgf / cmg = 9.81 · 10 ^{4} n / m ^{2} = 0.980655 bar = 0.980655 · 10 ^{6} dyne / cm ^{2} = 0, 968 atm = 735 torr | at | at | |

Millimeter of mercury = 133.32 n / m ^{2} | mm Hg st. | mm Hg | |

Thor - the name of the off-system unit of pressure, equal to 1 mm Hg. v .; given in honor of the Italian scientist E. Torricelli | torus | ||

Bar - a unit of atmospheric pressure = 1 · 10 ^{5} n / m ^{2} = 1 · 10 ^{6} dyn / cm ^{2} | bar | bar | |

Pressure (sound) | Bar — a unit of sound pressure (in acoustics): bar — 1 dyne / cm ^{2} ; currently, a unit with a value of 1 n / m ^{2} = 10 dyn / cm ^{2 is} recommended as a unit of sound pressure | bar | bar |

Decibel is a logarithmic unit for measuring the level of excess sound pressure, equal to 1/10 of the unit for measuring excessive pressure — white | dB | db | |

Temperature | Degree Celsius; temperature in ° K (Kelvin scale) is equal to temperature in ° C (Celsius scale) + 273.15 ° C | FROM | FROM |

Ii. Strength, power, energy, work, amount of heat, viscosity | |||

Force | Dina is the unit of force in the CGS system (cm-g-sec.), At which an acceleration equal to 1 cm / s ^{2 is} reported to a body with a mass of 1 g; 1 din - 1 · 10 ^{-5} n | din | dyn |

Kilogram-force is a force that imparts an acceleration equal to 9.81 m / s ^{2 to a} body with a mass of 1 kg; 1 kg = 9.81 n = 9.81 · 10 ^{5} dyn | kg, kgf | ||

Power | Horsepower = 735.5 W | l from. | HP |

Energy | Electron-volt is the energy that an electron acquires when moving in an electric field in a vacuum between points with a potential difference of 1 volt; 1 eV = 1.6 · 10 ^{-19} j. The use of multiple units is allowed: kiloelectron-volt (Kv) = 10 ^{3} eV and mega-electron-volt (MeV) = 10 ^{6} eV. In modern charged particle accelerators, particle energy is measured in BeV - billions (billions) eV; 1 bzv = 10 ^{9} eV | ev | eV |

Erg = 1 · 10 ^{-7} j; erg is also used as a unit of measurement of work, numerically equal to the work done by a force of 1 dyne on a path of 1 cm | erg | erg | |

Job | A kilogram-force meter (kilogrammeter) is a unit of work that is numerically equal to a work performed by a constant force of 1 kg when the point of application of this force is moved a distance of 1 m in its direction; 1kGm = 9.81 j (at the same time kGm is a measure of energy) | kgm, kgf · m | kGm |

Quantity of heat | Calorie is a non-systemic measure of the amount of heat equal to the amount of heat needed to heat 1 g of water from 19.5 ° C to 20.5 ° C. 1 cal = 4.187 J; multiple kilocalories (kcal, kcal) equal to 1000 calories | feces | cal |

Viscosity (dynamic) | Poise - a unit of viscosity in the system of units of the GHS; viscosity at which in a layered stream with a velocity gradient of 1 s ^{-1} per 1 cm ^{2 of the} surface of the layer, a viscosity force of 1 dyne acts; 1 pz = 0.1 n · s / m ^{2} | pz | P |

Viscosity (kinematic) | Stokes is the unit of kinematic viscosity in the GHS system; equal to the viscosity of a fluid having a density of 1 g / cm ^{3} , resisting a force of 1 din to the mutual displacement of two layers of fluid with an area of 1 cm ^{2} located 1 cm from each other and moving relative to each other at a speed of 1 cm per second | st | St |

III. Magnetic flux, magnetic induction, magnetic field strength, inductance, electrical capacitance | |||

Magnetic flux | Maxwell is the unit of measurement of the magnetic flux in the GHS system; 1 μs is equal to the magnetic flux passing through a 1 cm ^{2 area} , located perpendicular to the magnetic field induction lines, with an induction equal to 1 G; 1 µs = 10 ^{-8} WB (Weber) - units of magnetic current in the SI system | ms | Mx |

Magnetic induction | Gauss is a unit of measurement in the GHS system; 1 gs is the induction of such a field, in which a straight conductor with a length of 1 cm, located perpendicular to the field vector, experiences a force of 1 din if a current of 3 · 10 ^{10} CGS flows through this conductor; 1 gf = 1 · 10 ^{-4} T (Tesla) | gf | Gs |

Magnetic field strength | Oersted is a unit of magnetic field strength in the CS system; for one Oersted (1 Oe), the intensity at such a point of the field is taken, in which a 1 din (din) force acts on 1 electromagnetic unit of magnetism; 1 e = 1 / 4π · 10 ^{3} a / m | uh | Oe |

Inductance | Centimeter is the inductance unit in the GHS system; 1 cm = 1 · 10 ^{-9} g (henry) | cm | cm |

Electric capacity | Centimeter - unit capacity in the system GHS = 1 · 10 ^{-12} f (farad) | cm | cm |

Iv. Luminous intensity, luminous flux, brightness, illumination | |||

The power of light | A candle is a unit of luminous intensity, the value of which is taken such that the brightness of the full emitter at the solidification temperature of platinum is equal to 60 cc per 1 cm ^{2} | St. | cd |

Light flow | Lumen - a unit of luminous flux; 1 lumen (lm) is emitted within a solid angle of 1 erased by a point source of light having a luminous intensity in all directions | lm | lm |

Lumen-second - corresponds to the light energy generated by the luminous flux of 1 lm, emitted or perceived in 1 second | lm · s | lm · sec | |

Lumen-hour is equal to 3600 lumens-seconds | lm h | lm · h | |

Brightness | Stilb is the unit of brightness in the GHS system; corresponds to the brightness of a flat surface, 1 cm ^{2 of} which gives in the direction perpendicular to this surface a luminous intensity equal to 1 ce; 1 Sat = 1 · 10 ^{4} nt (nit) (unit of brightness in the SI system) | Sat | sb |

Lambert is an off-system luminance unit, derived from stilb; ст= 3193 нт 1 Lambert = 1 / π St = 3193 nt | |||

св/м ^{2} Apostilb = 1 / π sv / m ^{2} | |||

Illumination | Phot - the unit of illumination in the system SGSL (cm-g-sec-lm); 1 ph corresponds to the surface illumination in 1 cm ^{2} uniformly distributed luminous flux in 1 lm; 1 f = 1 · 10 ^{4} lx (suite) | f | ph |

V. Radiation Intensity and Dose | |||

Radioactivity intensity | Curie is the basic unit of measurement of the intensity of radioactive radiation, Curie corresponding to 3.7 · 10 ^{10} decays per second. any radioactive isotope | Curie | C or Cu |

millicurie = 10 ^{-3} curie, or 3.7 · 10 ^{7} acts of radioactive decay per second. | mkuri | mc or mCu | |

microcurie = 10 ^{-6} curie | mkkyuri | C или μ Cu μ C or μ Cu | |

Dose | -лучей, которое в 0,001293 г воздуха (т. е. в 1 см ^{3} сухого воздуха при t° 0° и 760 мм рт. ст.) вызывает образование ионов, несущих одну электростатическую единицу количества электричества каждого знака; X-ray - the amount (dose) of X-rays or γ rays, which in 0.001293 g of air (i.e. in 1 cm ^{3 of} dry air at t ° 0 ° and 760 mm Hg) causes the formation of ions carrying one electrostatic unit of quantity of electricity of each sign; 1 p causes the formation of 2.08 · 10 ^{9} pairs of ions in 1 cm ^{3 of} air | R | r |

milli-ray = 10 ^{-3} p | mr | mr | |

micro x-ray = 10 ^{-6} p | md | μr | |

Rad - the unit of the absorbed dose of any ionizing radiation is equal to rad 100 erg per 1 g of the irradiated medium; when air is ionized by x-rays or γ rays, 1 r is equal to 0.88 rad, and when ionizing tissues, almost 1 r is 1 rad | glad | rad | |

A rem (biological equivalent of X-ray) is the amount (dose) of any type of ionizing radiation that causes the same biological effect as 1 p (or 1 rad) of hard x-rays. The unequal biological effect with equal ionization by different types of radiation led to the need to introduce another concept: the relative biological efficiency of radiation — OBE; -лучей и ОБЭ=10 для протонов до 10 Мэв, быстрых нейтронов и α-ча стиц естественных (по рекомендации Международного конгресса радиологов в Копенгагене, 1953) the relationship between doses (D) and the dimensionless coefficient (RBE) is expressed as D _{rem} = D _{rad} · RBE, where RBE = 1 for x-rays, γ rays and β rays, and RBE = 10 for protons up to 10 MeV, fast neutrons and α - ha vits natural (on the recommendation of the International Congress of Radiologists in Copenhagen, 1953) | rem, reb | rem |

Note. Multiples and submultiples of measurement, with the exception of the units of time and angle, are formed by multiplying them by the corresponding power of the number 10, and their names are attached to the names of the units of measurement. It is not allowed to use two prefixes to the name of the unit. For example, you can not write a millimikrovatt (mmkvt) or micromicofarad (mmf), but you must write nanowatt (nvt) or picofarad (pf). Do not use prefixes for the names of such units that denote a multiple or partial unit of measurement (for example, microns). To express the duration of processes and designate calendar dates of events, the use of multiple time units is allowed.

### Major units of the International System of Units (SI)

**Basic units**

(length, mass, temperature, time, electric current, luminous intensity)

Name of the value | Units; their definition | Legend | |
---|---|---|---|

Russian | inter-national | ||

Length | Meter - length equal to 1650763.73 radiation wavelengths in vacuum, corresponding to the transition between the levels of 2p _{10} and 5d _{5} krypton atoms 86 * | m | m |

Weight | Kilogram - the mass corresponding to the mass of the international standard kilogram | kg | kg |

Time | Second - 1 / 31556925,9747 part of the tropical year (1900) ** | sec | S, s |

Electric current | Amp - a force of unchanging current, which, passing through two parallel straight conductors of infinite length and a negligible circular section, located at a distance of 1 m one from another in a vacuum, would cause between these conductors a force equal to 2 · 10 ^{-7} N per meter lengths | a | A |

The power of light | A candle is a unit of luminous intensity, the value of which is taken such that the brightness of the full (absolutely black) emitter at the solidification temperature of platinum is 60 ce per 1 cm ^{2} *** | St. | cd |

Temperature (thermodynamic) | Degree Kelvin (Kelvin scale) - a unit of temperature measurement on a thermodynamic temperature scale, in which the temperature of the triple point of water **** is set to 273.16 ° K | TO | ° K |

** That is, the second is equal to the indicated part of the time interval between two consecutive passages of the point in the orbit around the Sun to the point corresponding to the spring equinox. This gives greater accuracy in determining the second than determining it as part of the day, because the length of the day varies.

*** That is, the unit is taken as the luminous intensity of a specific reference source emitting light at the melting point of platinum. The former international benchmark candle is 1.005 new benchmark candles. Thus, within the limits of usual practical accuracy, their values can be considered coincident.

**** Triple point - the temperature of melting ice in the presence of saturated water vapor above it.

### Complementary and derived units

Name of the value | Units; their definition | Legend | |
---|---|---|---|

Russian | inter-national | ||

I. Flat angle, solid angle, force, work, energy, amount of heat, power | |||

Flat angle | Radian - the angle between two radii of a circle, cutting an arc on a circle with a arc, whose length is equal to the radius | glad | rad |

Solid angle | Steradian - a solid angle whose top is located in the center of a sphere is erased and which cuts an area on the surface of the sphere equal to the area of a square with a side equal to the radius of the sphere | erased | sr |

Force | Newton - force, under the action of which a body with a mass of 1 kg acquires an acceleration equal to 1 m / s ^{2} | n | N |

Work, energy, amount of heat | Joule - the work done by a constant force acting on a body in 1 n on a path of 1 m, passed by the body in the direction of the force | j | J |

Power | Watt - power at which for 1 sec. work is done in 1 j | W | W |

Ii. Amount of electricity, electrical voltage, electrical resistance, electrical capacity | |||

Amount of electricity, electric charge | Pendant - the amount of electricity flowing through the cross section of the conductor for 1 sec. with a dc power of 1 a | to | C |

Voltage, electric potential difference, electromotive force (EMF) | Volt - voltage on the section of the electric circuit, when passing through the amount of electricity in 1 to the work is done in 1 j | at | V |

Electrical resistance | Ohm - the resistance of the conductor, through which at a constant voltage at the ends of 1 V there is a direct current of 1 a | om | Ω |

Electric capacity | Farad is the capacitance of the capacitor, the voltage between the plates of which changes by 1 in when charged with an amount of electricity of 1 k | f | F |

III. Magnetic induction, flux magnetic induction, inductance, frequency | |||

Magnetic induction | Tesla — induction of a uniform magnetic field, which acts on a section of a straight conductor of 1 m in length, placed perpendicular to the direction of the field, acts with a force of 1 n as it passes through a direct current conductor of 1 a | tl | T |

Magnetic induction flow | Weber is a magnetic flux created by a uniform field with a magnetic induction of 1 T through a 1 m ^{2 area} perpendicular to the direction of the vector of magnetic induction | WB | Wb |

Inductance | Henry is the inductance of a conductor (coil) in which an emf is induced at 1 volt when the current in it is changed by 1 a per 1 sec. | gn | H |

Frequency | Hertz - the frequency of a periodic process, which for 1 sec. one oscillation is performed (cycle, period) | Hz | Hz |

Iv. Luminous flux, light energy, brightness, illumination | |||

Light flow | Lumen - the luminous flux that gives inside a solid angle of 1 erased a point source of light of 1 cb, radiating equally in all directions | lm | lm |

Light energy | Lumen second | lm · s | lm · s |

Brightness | Nit is the luminosity of a luminous plane, each square meter of which gives in the direction perpendicular to the plane a luminous intensity of 1 st | nt | nt |

Illumination | Lux - illumination created by a luminous flux of 1 lm with its uniform distribution over an area of 1 m ^{2} | lx | lx |

Amount of lighting | Lux second | lx · s | lx · s |