Symbol of work in physics. Basic physical quantities, their letter designations in physics. Physics and basic physical quantities
STATE SECURITY SYSTEM
UNITS OF MEASUREMENT
UNITS OF PHYSICAL QUANTITIES
GOST 8.417-81
(ST SEV 1052-78)
USSR STATE COMMITTEE ON STANDARDS
Moscow
DEVELOPED USSR State Committee for Standards PERFORMERSYu.V. Tarbeev,Dr.Tech. sciences; K.P. Shirokov,Dr.Tech. sciences; P.N. Selivanov, Ph.D. tech. sciences; ON THE. EryukhinaINTRODUCED USSR State Committee for Standards Member of Gosstandart OK. IsaevAPPROVED AND PUT INTO EFFECT Resolution of the USSR State Committee on Standards dated March 19, 1981 No. 1449STATE STANDARD OF THE USSR UNION
State system for ensuring the uniformity of measurements UNITSPHYSICALSIZE State system for ensuring the uniformity of measurements. Units of physical quantities |
GOST 8.417-81 (ST SEV 1052-78) |
from 01/01/1982
This standard establishes units of physical quantities (hereinafter referred to as units) used in the USSR, their names, designations and rules for the use of these units. The standard does not apply to units used in scientific research and in the publication of their results, if they do not consider and use the results measurements of specific physical quantities, as well as units of quantities assessed on conventional scales*. * Conventional scales mean, for example, the Rockwell and Vickers hardness scales and the photosensitivity of photographic materials. The standard complies with ST SEV 1052-78 in terms of general provisions, units of the International System, units not included in the SI, rules for the formation of decimal multiples and submultiples, as well as their names and designations, rules for writing unit designations, rules for the formation of coherent derived SI units ( see reference appendix 4).
1. GENERAL PROVISIONS
1.1. The units of the International System of Units*, as well as decimal multiples and submultiples of them, are subject to mandatory use (see Section 2 of this standard). * International System of Units (international abbreviated name - SI, in Russian transcription - SI), adopted in 1960 by the XI General Conference on Weights and Measures (GCPM) and refined at subsequent CGPM. 1.2. It is allowed to use, along with the units according to clause 1.1, units that are not included in the SI, in accordance with clauses. 3.1 and 3.2, their combinations with SI units, as well as some decimal multiples and submultiples of the above units that are widely used in practice. 1.3. It is temporarily allowed to use, along with the units under clause 1.1, units that are not included in SI, in accordance with clause 3.3, as well as some multiples and submultiples of them that have become widespread in practice, combinations of these units with SI units, decimal multiples and submultiples of them them and with units according to clause 3.1. 1.4. In newly developed or revised documentation, as well as publications, the values of quantities must be expressed in SI units, decimal multiples and fractions of them and (or) in units allowed for use in accordance with clause 1.2. It is also allowed in the specified documentation to use units according to clause 3.3, the withdrawal period of which will be established in accordance with international agreements. 1.5. The newly approved normative and technical documentation for measuring instruments must provide for their calibration in SI units, decimal multiples and fractions of them, or in units allowed for use in accordance with clause 1.2. 1.6. Newly developed regulatory and technical documentation on verification methods and means must provide for verification of measuring instruments calibrated in newly introduced units. 1.7. SI units established by this standard and units allowed for use in paragraphs. 3.1 and 3.2 should be used in educational processes of all educational institutions, in textbooks and teaching aids. 1.8. Revision of regulatory, technical, design, technological and other technical documentation in which units not provided for by this standard are used, as well as bringing into compliance with paragraphs. 1.1 and 1.2 of this standard for measuring instruments, graduated in units subject to withdrawal, are carried out in accordance with clause 3.4 of this standard. 1.9. In contractual-legal relations for cooperation with foreign countries, with participation in the activities of international organizations, as well as in technical and other documentation supplied abroad along with export products (including transport and consumer packaging), international designations of units are used. In documentation for export products, if this documentation is not sent abroad, it is allowed to use Russian unit designations. (New edition, Amendment No. 1). 1.10. In regulatory and technical design, technological and other technical documentation for various types of products and products used only in the USSR, Russian unit designations are preferably used. At the same time, regardless of what unit designations are used in the documentation for measuring instruments, when indicating units of physical quantities on plates, scales and shields of these measuring instruments, international unit designations are used. (New edition, Amendment No. 2). 1.11. In printed publications it is allowed to use either international or Russian designations of units. The simultaneous use of both types of symbols in the same publication is not allowed, with the exception of publications on units of physical quantities.2. UNITS OF THE INTERNATIONAL SYSTEM
2.1. The main SI units are given in table. 1.Table 1
Magnitude |
|||||
Name |
Dimension |
Name |
Designation |
Definition |
|
international |
|||||
Length | A meter is the length of the path traveled by light in a vacuum during a time interval of 1/299,792,458 S [XVII CGPM (1983), Resolution 1]. | ||||
Weight |
kilogram |
The kilogram is a unit of mass equal to the mass of the international prototype of the kilogram [I CGPM (1889) and III CGPM (1901)] | |||
Time | A second is a time equal to 9192631770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom [XIII CGPM (1967), Resolution 1] | ||||
Electric current strength | An ampere is a force equal to the strength of a constant current, which, when passing through two parallel straight conductors of infinite length and an insignificantly small circular cross-sectional area, located in a vacuum at a distance of 1 m from each other, would cause on each section of the conductor 1 m in length an interaction force equal to 2 × 10 -7 N [CIPM (1946), Resolution 2, approved by the IX CGPM (1948)] | ||||
Thermodynamic temperature | Kelvin is a unit of thermodynamic temperature equal to 1/273.16 of the thermodynamic temperature of the triple point of water [XIII CGPM (1967), Resolution 4] | ||||
Quantity of substance | A mole is the amount of substance in a system containing the same number of structural elements as there are atoms in carbon-12 weighing 0.012 kg. When using a mole, the structural elements must be specified and may be atoms, molecules, ions, electrons and other particles or specified groups of particles [XIV CGPM (1971), Resolution 3] | ||||
The power of light | Candela is the intensity equal to the luminous intensity in a given direction of a source emitting monochromatic radiation with a frequency of 540 × 10 12 Hz, the energetic luminous intensity of which in that direction is 1/683 W/sr [XVI CGPM (1979), Resolution 3] | ||||
Notes: 1. In addition to the Kelvin temperature (symbol T) it is also possible to use Celsius temperature (designation t), defined by the expression t = T - T 0 , where T 0 = 273.15 K, by definition. Kelvin temperature is expressed in Kelvin, Celsius temperature - in degrees Celsius (international and Russian designation °C). The size of a degree Celsius is equal to a kelvin. 2. Kelvin temperature interval or difference is expressed in kelvins. The Celsius temperature interval or difference can be expressed in both kelvins and degrees Celsius. 3. The designation of International Practical Temperature in the 1968 International Practical Temperature Scale, if it is necessary to distinguish it from thermodynamic temperature, is formed by adding the index “68” to the designation of thermodynamic temperature (for example, T 68 or t 68). 4. The uniformity of light measurements is ensured in accordance with GOST 8.023-83. |
table 2
Name of quantity |
||||
Name |
Designation |
Definition |
||
international |
||||
Flat angle | A radian is the angle between two radii of a circle, the length of the arc between which is equal to the radius | |||
Solid angle |
steradian |
A steradian is a solid angle with a vertex at the center of the sphere, cutting out on the surface of the sphere an area equal to the area of a square with a side equal to the radius of the sphere |
Table 3
Examples of derived SI units, the names of which are formed from the names of basic and additional units
Magnitude |
||||
Name |
Dimension |
Name |
Designation |
|
international |
||||
Square |
square meter |
|||
Volume, capacity |
cubic meter |
|||
Speed |
meter per second |
|||
Angular velocity |
radians per second |
|||
Acceleration |
meters per second squared |
|||
Angular acceleration |
radian per second squared |
|||
Wave number |
meter to the minus first power |
|||
Density |
kilogram per cubic meter |
|||
Specific volume |
cubic meter per kilogram |
|||
ampere per square meter |
||||
ampere per meter |
||||
Molar concentration |
mole per cubic meter |
|||
Flow of ionizing particles |
second to the minus first power |
|||
Particle flux density |
second to the minus first power - meter to the minus second power |
|||
Brightness |
candela per square meter |
Table 4
Derived SI units with special names
Magnitude |
|||||
Name |
Dimension |
Name |
Designation |
Expression in terms of major and minor, SI units |
|
international |
|||||
Frequency | |||||
Strength, weight | |||||
Pressure, mechanical stress, elastic modulus | |||||
Energy, work, amount of heat |
m 2 × kg × s -2 |
||||
Power, energy flow |
m 2 × kg × s -3 |
||||
Electric charge (amount of electricity) | |||||
Electrical voltage, electrical potential, electrical potential difference, electromotive force |
m 2 × kg × s -3 × A -1 |
||||
Electrical capacity |
L -2 M -1 T 4 I 2 |
m -2 × kg -1 × s 4 × A 2 |
|||
m 2 × kg × s -3 × A -2 |
|||||
Electrical conductivity |
L -2 M -1 T 3 I 2 |
m -2 × kg -1 × s 3 × A 2 |
|||
Magnetic induction flux, magnetic flux |
m 2 × kg × s -2 × A -1 |
||||
Magnetic flux density, magnetic induction |
kg × s -2 × A -1 |
||||
Inductance, mutual inductance |
m 2 × kg × s -2 × A -2 |
||||
Light flow | |||||
Illumination |
m -2 × cd × sr |
||||
Activity of a nuclide in a radioactive source (radionuclide activity) |
becquerel |
||||
Absorbed dose of radiation, kerma, absorbed dose indicator (absorbed dose of ionizing radiation) | |||||
Equivalent radiation dose |
Table 5
Examples of derived SI units, the names of which are formed using the special names given in table. 4
Magnitude |
|||||
Name |
Dimension |
Name |
Designation |
Expression in terms of SI major and supplementary units |
|
international |
|||||
Moment of power |
newton meter |
m 2 × kg × s -2 |
|||
Surface tension |
Newton per meter |
||||
Dynamic viscosity |
pascal second |
m -1 × kg × s -1 |
|||
pendant per cubic meter |
|||||
Electrical bias |
pendant per square meter |
||||
volt per meter |
m × kg × s -3 × A -1 |
||||
Absolute dielectric constant |
L -3 M -1 × T 4 I 2 |
farad per meter |
m -3 × kg -1 × s 4 × A 2 |
||
Absolute magnetic permeability |
henry per meter |
m × kg × s -2 × A -2 |
|||
Specific energy |
joule per kilogram |
||||
Heat capacity of the system, entropy of the system |
joule per kelvin |
m 2 × kg × s -2 × K -1 |
|||
Specific heat capacity, specific entropy |
joule per kilogram kelvin |
J/(kg × K) |
m 2 × s -2 × K -1 |
||
Surface energy flux density |
watt per square meter |
||||
Thermal conductivity |
watt per meter kelvin |
m × kg × s -3 × K -1 |
|||
joule per mole |
m 2 × kg × s -2 × mol -1 |
||||
Molar entropy, molar heat capacity |
L 2 MT -2 q -1 N -1 |
joule per mole kelvin |
J/(mol × K) |
m 2 × kg × s -2 × K -1 × mol -1 |
|
watt per steradian |
m 2 × kg × s -3 × sr -1 |
||||
Exposure dose (X-ray and gamma radiation) |
pendant per kilogram |
||||
Absorbed dose rate |
gray per second |
3. UNITS NOT INCLUDED IN SI
3.1. The units listed in table. 6 are allowed for use without a time limit, along with SI units. 3.2. Without a time limit, it is allowed to use relative and logarithmic units with the exception of the neper unit (see clause 3.3). 3.3. The units given in table. 7 may be temporarily applied until relevant international decisions are taken on them. 3.4. Units, the relationships of which with SI units are given in Reference Appendix 2, are withdrawn from circulation within the time limits provided for by the programs of measures for the transition to SI units, developed in accordance with RD 50-160-79. 3.5. In justified cases, in sectors of the national economy it is allowed to use units not provided for by this standard by introducing them into industry standards in agreement with Gosstandart.Table 6
Non-system units allowed for use along with SI units
Name of quantity |
Note |
||||
Name |
Designation |
Relation to SI unit |
|||
international |
|||||
Weight | |||||
atomic mass unit |
1.66057 × 10 -27 × kg (approx.) |
||||
Time 1 | |||||
86400 s |
|||||
Flat angle |
(p /180) rad = 1.745329… × 10 -2 × rad |
||||
(p /10800) rad = 2.908882… × 10 -4 rad |
|||||
(p /648000) rad = 4.848137…10 -6 rad |
|||||
Volume, capacity | |||||
Length |
astronomical unit |
1.49598 × 10 11 m (approx.) |
|||
light year |
9.4605 × 10 15 m (approx.) |
||||
3.0857 × 10 16 m (approx.) |
|||||
Optical power |
diopter |
||||
Square | |||||
Energy |
electron-volt |
1.60219 × 10 -19 J (approx.) |
|||
Full power |
volt-ampere |
||||
Reactive power | |||||
Mechanical stress |
newton per square millimeter |
||||
1 It is also possible to use other units that are widely used, for example, week, month, year, century, millennium, etc. 2 It is allowed to use the name “gon” 3 It is not recommended to use for precise measurements. If it is possible to shift the designation l with the number 1, the designation L is allowed. Note. Units of time (minute, hour, day), plane angle (degree, minute, second), astronomical unit, light year, diopter and atomic mass unit are not allowed to be used with prefixes |
Table 7
Units temporarily approved for use
Name of quantity |
Note |
||||
Name |
Designation |
Relation to SI unit |
|||
international |
|||||
Length |
nautical mile |
1852 m (exactly) |
In maritime navigation |
||
Acceleration |
In gravimetry |
||||
Weight |
2 × 10 -4 kg (exactly) |
For precious stones and pearls |
|||
Linear density |
10 -6 kg/m (exactly) |
In the textile industry |
|||
Speed |
In maritime navigation |
||||
Rotation frequency |
revolutions per second |
||||
revolutions per minute |
1/60 s -1 = 0.016(6) s -1 |
||||
Pressure | |||||
Natural logarithm of the dimensionless ratio of a physical quantity to the physical quantity of the same name, taken as the original |
1 Np = 0.8686…V = = 8.686… dB |
4. RULES FOR THE FORMATION OF DECIMAL MULTIPLES AND MULTIPLE UNITS, AS WELL AS THEIR NAMES AND DESIGNATIONS
4.1. Decimal multiples and submultiples, as well as their names and designations, should be formed using the factors and prefixes given in Table. 8.Table 8
Factors and prefixes for the formation of decimal multiples and submultiples and their names
Factor |
Console |
Prefix designation |
Factor |
Console |
Prefix designation |
||
international |
international |
||||||
5. RULES FOR WRITING UNIT DESIGNATIONS
5.1. To write the values of quantities, units should be designated with letters or special signs (...°,... ¢,... ¢ ¢), and two types of letter designations are established: international (using letters of the Latin or Greek alphabet) and Russian (using letters of the Russian alphabet) . The unit designations established by the standard are given in table. 1 - 7. International and Russian designations for relative and logarithmic units are as follows: percent (%), ppm (o/oo), ppm (pp m, ppm), bel (V, B), decibel (dB, dB), octave (- , oct), decade (-, dec), background (phon, background). 5.2. Letter designations of units must be printed in roman font. In unit designations, a dot is not used as an abbreviation sign. 5.3. Unit designations should be used after numerical values of quantities and placed on the line with them (without moving to the next line). Between the last digit of the number and the designation of the unit, a space should be left equal to the minimum distance between words, which is determined for each type and size of font according to GOST 2.304-81. Exceptions are designations in the form of a sign raised above the line (clause 5.1), before which a space is not left. (Changed edition, Amendment No. 3). 5.4. If there is a decimal fraction in the numerical value of a quantity, the unit symbol should be placed after all digits. 5.5. When indicating the values of quantities with maximum deviations, you should enclose the numerical values with maximum deviations in brackets and place unit designations after the brackets or put unit designations after the numerical value of the quantity and after its maximum deviation. 5.6. It is allowed to use unit designations in column headings and in row names (sidebars) of tables. Examples:
Nominal flow. m3/h |
Upper limit of readings, m 3 |
Dividing value of the rightmost roller, m 3, no more |
||
100, 160, 250, 400, 600 and 1000 |
||||
2500, 4000, 6000 and 10000 |
||||
Traction power, kW | ||||
Overall dimensions, mm: | ||||
length | ||||
width | ||||
height | ||||
Track, mm | ||||
Clearance, mm | ||||
APPLICATION 1
Mandatory
RULES FOR FORMATION OF COHERENT DERIVATIVE SI UNITS
Coherent derived units (hereinafter referred to as derived units) of the International System, as a rule, are formed using the simplest equations of connections between quantities (defining equations), in which the numerical coefficients are equal to 1. To form derived units, quantities in the connection equations are taken equal to SI units. Example. The unit of speed is formed using an equation that determines the speed of a rectilinearly and uniformly moving pointv = s/t,
Where v- speed; s- length of the traveled path; t- time of movement of the point. Substitution instead s And t their SI units gives
[v] = [s]/[t] = 1 m/s.
Therefore, the SI unit of speed is meter per second. It is equal to the speed of a rectilinearly and uniformly moving point, at which this point moves a distance of 1 m in a time of 1 s. If the communication equation contains a numerical coefficient different from 1, then to form a coherent derivative of an SI unit, values with values in SI units are substituted into the right-hand side, giving, after multiplication by the coefficient, a total numerical value equal to the number 1. Example. If the equation is used to form a unit of energy
Where E- kinetic energy; m is the mass of the material point; v is the speed of motion of a point, then the coherent SI unit of energy is formed, for example, as follows:
Therefore, the SI unit of energy is the joule (equal to the newton meter). In the examples given, it is equal to the kinetic energy of a body weighing 2 kg moving at a speed of 1 m / s, or a body weighing 1 kg moving at a speed
APPLICATION 2
Information
Correlation of some non-systemic units with SI units
Name of quantity |
Note |
||||
Name |
Designation |
Relation to SI unit |
|||
international |
|||||
Length |
angstrom |
||||
x-unit |
1.00206 × 10 -13 m (approx.) |
||||
Square | |||||
Weight | |||||
Solid angle |
square degree |
3.0462... × 10 -4 sr |
|||
Strength, weight | |||||
kilogram-force |
9.80665 N (exact) |
||||
kilopond |
|||||
gram-force |
9.83665 × 10 -3 N (exact) |
||||
ton-force |
9806.65 N (exactly) |
||||
Pressure |
kilogram-force per square centimeter |
98066.5 Ra (exactly) |
|||
kilopond per square centimeter |
|||||
millimeter of water column |
mm water Art. |
9.80665 Ra (exactly) |
|||
millimeter of mercury |
mmHg Art. |
||||
Tension (mechanical) |
kilogram-force per square millimeter |
9.80665 × 10 6 Ra (exact) |
|||
kilopond per square millimeter |
9.80665 × 10 6 Ra (exact) |
||||
Work, energy | |||||
Power |
Horsepower |
||||
Dynamic viscosity | |||||
Kinematic viscosity | |||||
ohm-square millimeter per meter |
Ohm × mm 2 /m |
||||
Magnetic flux |
Maxwell |
||||
Magnetic induction | |||||
gplbert |
(10/4 p) A = 0.795775…A |
||||
Magnetic field strength |
(10 3 / p) A/ m = 79.5775…A/ m |
||||
Amount of heat, thermodynamic potential (internal energy, enthalpy, isochoric-isothermal potential), heat of phase transformation, heat of chemical reaction |
calorie (int.) |
4.1858 J (exactly) |
|||
thermochemical calorie |
4.1840 J (approx.) |
||||
calorie 15 degrees |
4.1855 J (approx.) |
||||
Absorbed radiation dose | |||||
Equivalent dose of radiation, equivalent dose indicator | |||||
Exposure dose of photon radiation (exposure dose of gamma and x-ray radiation) |
2.58 × 10 -4 C/kg (exact) |
||||
Activity of a nuclide in a radioactive source |
3,700 × 10 10 Bq (exact) |
||||
Length | |||||
Angle of rotation |
2 p rad = 6.28… rad |
||||
Magnetomotive force, magnetic potential difference |
ampereturn |
||||
Brightness | |||||
Square |
APPLICATION 3
Information
1. The choice of a decimal multiple or fractional unit of an SI unit is dictated primarily by the convenience of its use. From the variety of multiple and submultiple units that can be formed using prefixes, a unit is selected that leads to numerical values of the quantity acceptable in practice. In principle, multiples and submultiples are chosen so that the numerical values of the quantity are in the range from 0.1 to 1000. 1.1. In some cases, it is appropriate to use the same multiple or submultiple unit even if the numerical values fall outside the range of 0.1 to 1000, for example, in tables of numerical values for the same quantity or when comparing these values in the same text. 1.2. In some areas the same multiple or submultiple unit is always used. For example, in drawings used in mechanical engineering, linear dimensions are always expressed in millimeters. 2. In table. 1 of this appendix shows the recommended multiples and submultiples of SI units for use. Presented in table. 1 multiples and submultiples of SI units for a given physical quantity should not be considered exhaustive, since they may not cover the ranges of physical quantities in developing and emerging fields of science and technology. However, the recommended multiples and submultiples of SI units contribute to the uniformity of presentation of the values of physical quantities related to various fields of technology. The same table also contains multiples and submultiples of units that are widely used in practice and are used along with SI units. 3. For quantities not covered in table. 1, you should use multiple and submultiple units selected in accordance with paragraph 1 of this appendix. 4. To reduce the likelihood of errors in calculations, it is recommended to substitute decimal multiples and submultiples only in the final result, and during the calculation process, express all quantities in SI units, replacing prefixes with powers of 10. 5. In Table. 2 of this appendix shows the popular units of some logarithmic quantities.Table 1
Name of quantity |
Designations |
|||
SI units |
units not included in SI |
multiples and submultiples of non-SI units |
||
Part I. Space and time |
||||
Flat angle |
rad ; rad (radian) |
m rad ; mkrad |
... ° (degree)... (minute)..." (second) |
|
Solid angle |
sr ; cp (steradian) |
|||
Length |
m; m (meter) |
… ° (degree) … ¢ (minute) … ² (second) |
||
Square | ||||
Volume, capacity |
l(L); l (liter) |
|||
Time |
s ; s (second) |
d ; day (day) min; min (minute) |
||
Speed | ||||
Acceleration |
m/s2; m/s 2 |
|||
Part II. Periodic and related phenomena |
||||
Hz ; Hz (hertz) |
||||
Rotation frequency |
min -1 ; min -1 |
|||
Part III. Mechanics |
||||
Weight |
kg ; kg (kilogram) |
t ; t (ton) |
||
Linear density |
kg/m; kg/m |
mg/m; mg/m or g/km; g/km |
||
Density |
kg/m3; kg/m 3 |
Mg/m3; Mg/m 3 kg/dm 3; kg/dm 3 g/cm3; g/cm 3 |
t/m3; t/m 3 or kg/l; kg/l |
g/ml; g/ml |
Quantity of movement |
kg×m/s; kg × m/s |
|||
Momentum |
kg × m 2 / s; kg × m 2 /s |
|||
Moment of inertia (dynamic moment of inertia) |
kg × m 2, kg × m 2 |
|||
Strength, weight |
N; N (newton) |
|||
Moment of power |
N×m; N×m |
MN × m; MN × m kN × m; kN × m mN × m; mN × m m N × m ; µN × m |
||
Pressure |
Ra; Pa (pascal) |
m Ra; µPa |
||
Voltage | ||||
Dynamic viscosity |
Ra × s; Pa × s |
mPa × s; mPa × s |
||
Kinematic viscosity |
m2/s; m 2 /s |
mm2/s; mm 2 /s |
||
Surface tension |
mN/m; mN/m |
|||
Energy, work |
J; J (joule) |
(electron-volt) |
GeV ; GeV MeV ; MeV keV ; keV |
|
Power |
W; W (watt) |
|||
Part IV. Heat |
||||
Temperature |
TO; K (kelvin) |
|||
Temperature coefficient | ||||
Heat, amount of heat | ||||
Heat flow | ||||
Thermal conductivity | ||||
Heat transfer coefficient |
W/(m 2 × K) |
|||
Heat capacity |
kJ/K; kJ/K |
|||
Specific heat |
J/(kg × K) |
kJ /(kg × K); kJ/(kg × K) |
||
Entropy |
kJ/K; kJ/K |
|||
Specific entropy |
J/(kg × K) |
kJ/(kg × K); kJ/(kg × K) |
||
Specific heat |
J/kg; J/kg |
MJ/kg; MJ/kg kJ / kg ; kJ/kg |
||
Specific heat of phase transformation |
J/kg; J/kg |
MJ/kg; MJ/kg kJ/kg; kJ/kg |
||
Part V. Electricity and magnetism |
||||
Electric current (electric current strength) |
A; A (amps) |
|||
Electric charge (amount of electricity) |
WITH; Cl (pendant) |
|||
Spatial density of electric charge |
C/ m 3; C/m 3 |
C/mm 3; C/mm 3 MS/ m 3 ; MC/m 3 S/s m 3 ; C/cm 3 kC/m3; kC/m 3 m C/ m 3; mC/m 3 m C/ m 3; µC/m 3 |
||
Surface electric charge density |
S/ m 2, C/m 2 |
MS/ m 2 ; MC/m 2 С/ mm 2; C/mm 2 S/s m 2 ; C/cm 2 kC/m2; kC/m 2 m C/ m 2; mC/m 2 m C/ m 2; µC/m 2 |
||
Electric field strength |
MV/m; MV/m kV/m; kV/m V/mm; V/mm V/cm; V/cm mV/m; mV/m mV/m; µV/m |
|||
Electrical voltage, electrical potential, electrical potential difference, electromotive force |
V, V (volts) |
|||
Electrical bias |
C/ m 2; C/m 2 |
S/s m 2 ; C/cm 2 kC/cm2; kC/cm 2 m C/ m 2; mC/m 2 m C/ m 2, µC/m 2 |
||
Electrical displacement flux | ||||
Electrical capacity |
F, Ф (farad) |
|||
Absolute dielectric constant, electrical constant |
m F / m , µF/m nF/m, nF/m pF / m , pF/m |
|||
Polarization |
S/ m 2, C/m 2 |
S/s m 2, C/cm 2 kC/m2; kC/m 2 m C/ m 2, mC/m 2 m C/ m 2; µC/m 2 |
||
Electric dipole moment |
S × m, Cl × m |
|||
Electric current density |
A/ m 2, A/m 2 |
MA/ m 2, MA/m 2 A/mm 2, A/mm 2 A/s m 2, A/cm 2 kA/m2, kA/m2, |
||
Linear electric current density |
kA/m; kA/m A/mm; A/mm A/c m ; A/cm |
|||
Magnetic field strength |
kA/m; kA/m A/mm; A/mm A/cm; A/cm |
|||
Magnetomotive force, magnetic potential difference | ||||
Magnetic induction, magnetic flux density |
T; Tl (tesla) |
|||
Magnetic flux |
Wb, Wb (weber) |
|||
Magnetic vector potential |
T × m; T × m |
kT×m; kT × m |
||
Inductance, mutual inductance |
N; Gn (Henry) |
|||
Absolute magnetic permeability, magnetic constant |
m N/ m; µH/m nH/m; nH/m |
|||
Magnetic moment |
A × m 2; A m 2 |
|||
Magnetization |
kA/m; kA/m A/mm; A/mm |
|||
Magnetic polarization | ||||
Electrical resistance | ||||
Electrical conductivity |
S ; CM (Siemens) |
|||
Electrical resistivity |
W×m; Ohm × m |
GW×m; GΩ × m M W × m; MΩ × m kW×m; kOhm × m W×cm; Ohm × cm mW×m; mOhm × m mW×m; µOhm × m nW×m; nOhm × m |
||
Electrical conductivity |
MS/m; MSm/m kS/m; kS/m |
|||
Reluctance | ||||
Magnetic conductivity | ||||
Impedance | ||||
Impedance module | ||||
Reactance | ||||
Active resistance | ||||
Admittance | ||||
Conductivity module | ||||
Reactive conductivity | ||||
Conductance | ||||
Active power | ||||
Reactive power | ||||
Full power |
V × A, V × A |
|||
Part VI. Light and related electromagnetic radiation |
||||
Wavelength | ||||
Wave number | ||||
Radiation energy | ||||
Radiation flux, radiation power | ||||
Energy luminous intensity (radiant intensity) |
W/sr; Tue/Wed |
|||
Energy brightness (radiance) |
W /(sr × m 2); W/(avg × m2) |
|||
Energy illumination (irradiance) |
W/m2; W/m2 |
|||
Energetic luminosity (radiance) |
W/m2; W/m2 |
|||
The power of light | ||||
Light flow |
lm ; lm (lumen) |
|||
Light energy |
lm×s; lm × s |
lm × h; lm × h |
||
Brightness |
cd/m2; cd/m2 |
|||
Luminosity |
lm/m2; lm/m 2 |
|||
Illumination |
l x; lux (lux) |
|||
Light exposure |
lx×s; lx × s |
|||
Light equivalent of radiation flux |
lm/W; lm/W |
|||
Part VII. Acoustics |
||||
Period | ||||
Batch frequency | ||||
Wavelength | ||||
Sound pressure |
m Ra; µPa |
|||
Particle oscillation speed |
mm/s; mm/s |
|||
Volume velocity |
m3/s; m 3 /s |
|||
Sound speed | ||||
Sound energy flow, sound power | ||||
Sound intensity |
W/m2; W/m2 |
mW/m2; mW/m2 mW/m2; µW/m 2 pW/m2; pW/m2 |
||
Specific acoustic impedance |
Pa×s/m; Pa × s/m |
|||
Acoustic impedance |
Pa×s/m3; Pa × s/m 3 |
|||
Mechanical resistance |
N×s/m; N × s/m |
|||
Equivalent absorption area of a surface or object | ||||
Reverberation time | ||||
Part VIII Physical chemistry and molecular physics |
||||
Quantity of substance |
mol ; mole (mol) |
kmol; kmol mmol; mmol m mol ; µmol |
||
Molar mass |
kg/mol; kg/mol |
g/mol; g/mol |
||
Molar volume |
m3/moi; m 3 /mol |
dm 3/mol; dm 3 /mol cm 3 / mol; cm 3 /mol |
l/mol; l/mol |
|
Molar internal energy |
J/mol; J/mol |
kJ/mol; kJ/mol |
||
Molar enthalpy |
J/mol; J/mol |
kJ/mol; kJ/mol |
||
Chemical Potential |
J/mol; J/mol |
kJ/mol; kJ/mol |
||
Chemical affinity |
J/mol; J/mol |
kJ/mol; kJ/mol |
||
Molar heat capacity |
J/(mol × K); J/(mol × K) |
|||
Molar entropy |
J/(mol × K); J/(mol × K) |
|||
Molar concentration |
mol/m3; mol/m 3 |
kmol/m3; kmol/m 3 mol/dm 3; mol/dm 3 |
mol/1; mol/l |
|
Specific adsorption |
mol/kg; mol/kg |
mmol/kg; mmol/kg |
||
Thermal diffusivity |
M2/s; m 2 /s |
|||
Part IX. Ionizing radiation |
||||
Absorbed dose of radiation, kerma, absorbed dose indicator (absorbed dose of ionizing radiation) |
Gy ; Gr (gray) |
m G y; µGy |
||
Activity of a nuclide in a radioactive source (radionuclide activity) |
Bq ; Bq (becquerel) |
table 2
Name of logarithmic quantity |
Unit designation |
Initial value of the quantity |
Sound pressure level | ||
Sound power level | ||
Sound intensity level | ||
Power Level Difference | ||
Strengthening, weakening | ||
Attenuation coefficient |
APPLICATION 4
Information
INFORMATION DATA ABOUT COMPLIANCE WITH GOST 8.417-81 ST SEV 1052-78
1. Sections 1 - 3 (clauses 3.1 and 3.2); 4, 5 and the mandatory Appendix 1 to GOST 8.417-81 correspond to sections 1 - 5 and the appendix to ST SEV 1052-78. 2. Reference appendix 3 to GOST 8.417-81 corresponds to the information appendix to ST SEV 1052-78.In mathematics, symbols are used throughout the world to simplify and shorten text. Below is a list of the most common mathematical notations, corresponding commands in TeX, explanations and examples of use. In addition to those indicated... ... Wikipedia
A list of specific symbols used in mathematics can be seen in the article Table of mathematical symbols Mathematical notation (“the language of mathematics”) is a complex graphic system of notation used to present abstract ... ... Wikipedia
A list of sign systems (notation systems, etc.) used by human civilization, with the exception of writing systems, for which there is a separate list. Contents 1 Criteria for inclusion in the list 2 Mathematics ... Wikipedia
Paul Adrien Maurice Dirac Paul Adrien Maurice Dirac Date of birth: 8& ... Wikipedia
Dirac, Paul Adrien Maurice Paul Adrien Maurice Dirac Date of birth: August 8, 1902(... Wikipedia
Gottfried Wilhelm Leibniz Gottfried Wilhelm Leibniz ... Wikipedia
This term has other meanings, see Meson (meanings). Meson (from other Greek μέσος middle) boson of strong interaction. In the Standard Model, mesons are composite (not elementary) particles consisting of even... ... Wikipedia
Nuclear physics ... Wikipedia
Alternative theories of gravity are usually called theories of gravity that exist as alternatives to the general theory of relativity (GTR) or significantly (quantitatively or fundamentally) modify it. Towards alternative theories of gravity... ... Wikipedia
Alternative theories of gravity are usually called theories of gravity that exist as alternatives to the general theory of relativity or significantly (quantitatively or fundamentally) modify it. Alternative theories of gravity are often... ... Wikipedia
Drawing drawings is not an easy task, but you can’t do without it in the modern world. After all, in order to make even the most ordinary item (a tiny bolt or nut, a shelf for books, the design of a new dress, etc.), you first need to carry out the appropriate calculations and draw a drawing of the future product. However, often one person draws it up, and another person produces something according to this scheme.
To avoid confusion in understanding the depicted object and its parameters, conventions for length, width, height and other quantities used in design are accepted all over the world. What are they? Let's find out.
Quantities
Area, height and other designations of a similar nature are not only physical, but also mathematical quantities.
Their single letter designation (used by all countries) was established in the mid-twentieth century by the International System of Units (SI) and is still used to this day. It is for this reason that all such parameters are indicated in Latin, and not in Cyrillic letters or Arabic script. In order not to create certain difficulties, when developing design documentation standards in most modern countries, it was decided to use almost the same conventions that are used in physics or geometry.
Any school graduate remembers that depending on whether a two-dimensional or three-dimensional figure (product) is depicted in the drawing, it has a set of basic parameters. If there are two dimensions, these are width and length, if there are three, height is also added.
So, first, let's find out how to correctly indicate length, width, height in the drawings.
Width
As mentioned above, in mathematics the quantity in question is one of the three spatial dimensions of any object, provided that its measurements are made in the transverse direction. So what is width famous for? It is designated by the letter “B”. This is known all over the world. Moreover, according to GOST, it is permissible to use both capital and lowercase Latin letters. The question often arises as to why this particular letter was chosen. After all, the reduction is usually made according to the first Greek or English name of the quantity. In this case, the width in English will look like “width”.
Probably the point here is that this parameter was initially most widely used in geometry. In this science, when describing figures, length, width, height are often denoted by the letters “a”, “b”, “c”. According to this tradition, when choosing, the letter "B" (or "b") was borrowed from the SI system (although symbols other than geometric ones began to be used for the other two dimensions).
Most believe that this was done so as not to confuse width (designated with the letter "B"/"b") with weight. The fact is that the latter is sometimes referred to as “W” (short for the English name weight), although the use of other letters (“G” and “P”) is also acceptable. According to international standards of the SI system, width is measured in meters or multiples (multiples) of their units. It is worth noting that in geometry it is sometimes also acceptable to use “w” to denote width, but in physics and other exact sciences such a designation is usually not used.
Length
As already indicated, in mathematics, length, height, width are three spatial dimensions. Moreover, if width is a linear dimension in the transverse direction, then length is in the longitudinal direction. Considering it as a quantity of physics, one can understand that this word means a numerical characteristic of the length of lines.
In English this term is called length. It is because of this that this value is denoted by the capital or lowercase initial letter of the word - “L”. Like width, length is measured in meters or their multiples (multiples).
Height
The presence of this value indicates that we have to deal with a more complex - three-dimensional space. Unlike length and width, height numerically characterizes the size of an object in the vertical direction.
In English it is written as "height". Therefore, according to international standards, it is denoted by the Latin letter “H” / “h”. In addition to height, in drawings sometimes this letter also acts as a designation for depth. Height, width and length - all these parameters are measured in meters and their multiples and submultiples (kilometers, centimeters, millimeters, etc.).
Radius and diameter
In addition to the parameters discussed, when drawing up drawings you have to deal with others.
For example, when working with circles, it becomes necessary to determine their radius. This is the name of the segment that connects two points. The first of them is the center. The second is located directly on the circle itself. In Latin this word looks like "radius". Hence the lowercase or capital “R”/“r”.
When drawing circles, in addition to the radius, you often have to deal with a phenomenon close to it - diameter. It is also a line segment connecting two points on a circle. In this case, it necessarily passes through the center.
Numerically, the diameter is equal to two radii. In English this word is written like this: "diameter". Hence the abbreviation - large or small Latin letter “D” / “d”. Often the diameter in the drawings is indicated using a crossed out circle - “Ø”.
Although this is a common abbreviation, it is worth keeping in mind that GOST provides for the use of only the Latin “D” / “d”.
Thickness
Most of us remember school mathematics lessons. Even then, teachers told us that it is customary to use the Latin letter “s” to denote a quantity such as area. However, according to generally accepted standards, a completely different parameter is written in drawings in this way - thickness.
Why is that? It is known that in the case of height, width, length, the designation by letters could be explained by their writing or tradition. It’s just that thickness in English looks like “thickness”, and in Latin it looks like “crassities”. It is also not clear why, unlike other quantities, thickness can only be indicated in lowercase letters. The notation "s" is also used to describe the thickness of pages, walls, ribs, etc.
Perimeter and area
Unlike all the quantities listed above, the word “perimeter” does not come from Latin or English, but from Greek. It is derived from "περιμετρέο" ("measure the circumference"). And today this term has retained its meaning (the total length of the boundaries of the figure). Subsequently, the word entered the English language (“perimeter”) and was fixed in the SI system in the form of an abbreviation with the letter “P”.
Area is a quantity that shows the quantitative characteristics of a geometric figure that has two dimensions (length and width). Unlike everything listed earlier, it is measured in square meters (as well as in submultiples and multiples thereof). As for the letter designation of the area, it differs in different areas. For example, in mathematics this is the Latin letter “S”, familiar to everyone since childhood. Why this is so - no information.
Some people unknowingly think that this is due to the English spelling of the word "square". However, in it the mathematical area is "area", and "square" is the area in the architectural sense. By the way, it is worth remembering that “square” is the name of the geometric figure “square”. So you should be careful when studying drawings in English. Due to the translation of “area” in some disciplines, the letter “A” is used as a designation. In rare cases, "F" is also used, but in physics this letter stands for a quantity called "force" ("fortis").
Other common abbreviations
The designations for height, width, length, thickness, radius, and diameter are the most commonly used when drawing up drawings. However, there are other quantities that are also often present in them. For example, lowercase "t". In physics, this means “temperature”, however, according to GOST of the Unified System of Design Documentation, this letter is the pitch (of helical springs, etc.). However, it is not used when it comes to gears and threads.
The capital and lowercase letter “A”/“a” (according to the same standards) in the drawings is used to denote not the area, but the center-to-center and center-to-center distance. In addition to different sizes, in drawings it is often necessary to indicate angles of different sizes. For this purpose, it is customary to use lowercase letters of the Greek alphabet. The most commonly used are “α”, “β”, “γ” and “δ”. However, it is acceptable to use others.
What standard defines the letter designation of length, width, height, area and other quantities?
As mentioned above, so that there is no misunderstanding when reading the drawing, representatives of different nations have adopted common standards for letter designation. In other words, if you are in doubt about the interpretation of a particular abbreviation, look at GOSTs. This way you will learn how to correctly indicate height, width, length, diameter, radius, and so on.
The times when current was discovered through the personal sensations of scientists who passed it through themselves are long gone. Now special devices called ammeters are used for this.
An ammeter is a device used to measure current. What is meant by current strength?
Let's look at Figure 21, b. It shows the cross section of the conductor through which charged particles pass when there is an electric current in the conductor. In a metal conductor, these particles are free electrons. As electrons move along a conductor, they carry some charge. The more electrons and the faster they move, the more charge they will transfer in the same time.
Current strength is a physical quantity that shows how much charge passes through the cross section of a conductor in 1 s.
Let, for example, during a time t = 2 s, current carriers carry a charge of q = 4 C through the cross section of the conductor. The charge transferred by them in 1 s will be 2 times less. Dividing 4 C by 2 s, we get 2 C/s. This is the current strength. It is designated by the letter I:
I - current strength.
So, to find the current strength I, it is necessary to divide the electric charge q that passed through the cross section of the conductor in time t by this time:
The unit of current is called ampere (A) in honor of the French scientist A. M. Ampere (1775-1836). The definition of this unit is based on the magnetic effect of current, and we will not dwell on it. If the current strength I is known, then we can find the charge q passing through the cross section of the conductor in time t. To do this, you need to multiply the current by time:
The resulting expression allows us to determine the unit of electric charge - coulomb (C):
1 C = 1 A 1 s = 1 A s.
1 C is the charge that passes through the cross-section of a conductor in 1 s at a current of 1 A.
In addition to the ampere, other (multiple and sub-multiple) units of current strength are often used in practice, for example milliampere (mA) and microampere (µA):
1 mA = 0.001 A, 1 µA = 0.000001 A.
As already mentioned, current is measured using ammeters (as well as milli- and microammeters). The demonstration galvanometer mentioned above is a conventional microammeter.
There are different designs of ammeters. The ammeter, intended for demonstration experiments at school, is shown in Figure 28. The same figure shows its symbol (a circle with the Latin letter “A” inside). When connected to a circuit, an ammeter, like any other measuring device, should not have a noticeable effect on the measured value. Therefore, the ammeter is designed in such a way that when it is turned on, the current strength in the circuit remains almost unchanged.
Depending on the purpose, ammeters with different division values are used in technology. The ammeter scale shows what maximum current it is designed for. You cannot connect it to a circuit with a higher current strength, as the device may deteriorate.
To connect the ammeter to the circuit, it is opened and the free ends of the wires are connected to the terminals (clamps) of the device. In this case, the following rules must be observed:
1) the ammeter is connected in series with the circuit element in which the current is measured;
2) the ammeter terminal with the “+” sign should be connected to the wire that comes from the positive pole of the current source, and the terminal with the “–” sign - to the wire that comes from the negative pole of the current source.
When connecting an ammeter to a circuit, it does not matter which side (left or right) of the element being tested it is connected to. This can be verified experimentally (Fig. 29). As you can see, when measuring the current passing through the lamp, both ammeters (the one on the left and the one on the right) show the same value.
1. What is current strength? What letter does it represent? 2. What is the formula for current strength? 3. What is the unit of current called? How is it designated? 4. What is the name of the device for measuring current? How is it indicated on the diagrams? 5. What rules should be followed when connecting an ammeter to a circuit? 6. What formula is used to find the electric charge passing through the cross section of a conductor if the current strength and the time of its passage are known?
phscs.ru
Basic physical quantities, their letter designations in physics.
It's no secret that there are special notations for quantities in any science. Letter designations in physics prove that this science is no exception in terms of identifying quantities using special symbols. There are quite a lot of basic quantities, as well as their derivatives, each of which has its own symbol. So, letter designations in physics are discussed in detail in this article.
Physics and basic physical quantities
Thanks to Aristotle, the word physics began to be used, since it was he who first used this term, which at that time was considered synonymous with the term philosophy. This is due to the commonality of the object of study - the laws of the Universe, more specifically - how it functions. As you know, the first scientific revolution took place in the 16th-17th centuries, and it was thanks to it that physics was singled out as an independent science.
Mikhail Vasilyevich Lomonosov introduced the word physics into the Russian language by publishing a textbook translated from German - the first physics textbook in Russia.
So, physics is a branch of natural science devoted to the study of the general laws of nature, as well as matter, its movement and structure. There are not as many basic physical quantities as it might seem at first glance - there are only 7 of them:
- length,
- weight,
- time,
- current strength,
- temperature,
- amount of substance
- the power of light.
Of course, they have their own letter designations in physics. For example, the symbol chosen for mass is m, and for temperature - T. Also, all quantities have their own unit of measurement: the luminous intensity is candela (cd), and the unit of measurement for the amount of substance is mole.
Derived physical quantities
There are much more derivative physical quantities than basic ones. There are 26 of them, and often some of them are attributed to the main ones.
So, area is a derivative of length, volume is also a derivative of length, speed is a derivative of time, length, and acceleration, in turn, characterizes the rate of change in speed. Momentum is expressed through mass and speed, force is the product of mass and acceleration, mechanical work depends on force and length, energy is proportional to mass. Power, pressure, density, surface density, linear density, amount of heat, voltage, electrical resistance, magnetic flux, moment of inertia, moment of impulse, moment of force - they all depend on mass. Frequency, angular velocity, angular acceleration are inversely proportional to time, and electric charge is directly dependent on time. Angle and solid angle are derived quantities from length.
What letter represents voltage in physics? Voltage, which is a scalar quantity, is denoted by the letter U. For speed, the designation is the letter v, for mechanical work - A, and for energy - E. Electric charge is usually denoted by the letter q, and magnetic flux - F.
SI: general information
The International System of Units (SI) is a system of physical units that is based on the International System of Units, including the names and designations of physical quantities. It was adopted by the General Conference on Weights and Measures. It is this system that regulates letter designations in physics, as well as their dimensions and units of measurement. Letters of the Latin alphabet are used for designation, and in some cases - of the Greek alphabet. It is also possible to use special characters as a designation.
Conclusion
So, in any scientific discipline there are special designations for various kinds of quantities. Naturally, physics is no exception. There are quite a lot of letter symbols: force, area, mass, acceleration, voltage, etc. They have their own symbols. There is a special system called the International System of Units. It is believed that basic units cannot be mathematically derived from others. Derivative quantities are obtained by multiplying and dividing from basic ones.
fb.ru
Area (Latin area), vector potential, work (German Arbeit), amplitude (Latin amplitudo), degeneracy parameter, work function (German Austrittsarbeit), Einstein coefficient for spontaneous emission, mass number | |
Acceleration (lat. acceleratio), amplitude (lat. amplitudo), activity (lat. activitas), thermal diffusivity coefficient, rotational ability, Bohr radius | |
Magnetic induction vector, baryon number, specific gas constant, virial coefficient, Brillouin function, interference fringe width (German Breite), brightness, Kerr constant, Einstein coefficient for stimulated emission, coefficient Einstein for absorption, rotational constant of the molecule | |
Magnetic induction vector, beauty/bottom quark, Wien constant, width (German: Breite) | |
electric capacity (eng. capacitance), heat capacity (eng. heatcapacity), constant of integration (lat. constans), charm (eng. charm), Clebsch-Gordan coefficients (eng. Clebsch-Gordan coefficients), Cotton-Mouton constant (eng. Cotton-Mouton constant), curvature (lat. curvatura) | |
Speed of light (Latin celeritas), speed of sound (Latin celeritas), heat capacity, magic quark, concentration, first radiation constant, second radiation constant | |
Electric displacement field vector, diffusion coefficient, dioptric power, transmission coefficient, quadrupole electric moment tensor, angular dispersion of a spectral device, linear dispersion of a spectral device, potential transparency coefficient barrier, de-plus meson (English Dmeson), de-zero meson (English Dmeson), diameter (Latin diametros, ancient Greek διάμετρος) | |
Distance (Latin distantia), diameter (Latin diametros, Ancient Greek διάμετρος), differential (Latin differentia), down quark, dipole moment, diffraction grating period, thickness (German: Dicke) | |
Energy (Latin energīa), electric field strength (English electric field), electromotive force (English electromotive force), magnetomotive force, illumination (French éclairement lumineux), emissivity of the body, Young's modulus | |
2.71828…, electron, elementary electric charge, electromagnetic interaction constant | |
Force (lat. fortis), Faraday constant, Helmholtz free energy (German freie Energie), atomic scattering factor, electromagnetic field strength tensor, magnetomotive force, shear modulus | |
Frequency (lat. frequentia), function (lat. functia), volatility (ger. Flüchtigkeit), force (lat. fortis), focal length (eng. focal length), oscillator strength, friction coefficient | |
Gravitational constant, Einstein tensor, Gibbs free energy, space-time metric, virial, partial molar value, adsorbate surface activity, shear modulus, total field momentum, gluon ), Fermi constant, conductivity quantum, electrical conductivity, weight (German: Gewichtskraft) | |
Gravitational acceleration, gluon, Lande factor, degeneracy factor, weight concentration, graviton, constant Gauge interactions | |
Magnetic field strength, equivalent dose, enthalpy (heat contents or from the Greek letter “eta”, H - ενθαλπος), Hamiltonian, Hankel function, Heaviside step function ), Higgs boson, exposure, Hermite polynomials | |
Height (German: Höhe), Planck's constant (German: Hilfsgröße), helicity (English: helicity) | |
current intensity (French intensité de courant), sound intensity (Latin intēnsiō), light intensity (Latin intēnsiō), radiation intensity, luminous intensity, moment of inertia, magnetization vector | |
Imaginary unit (lat. imaginarius), unit vector | |
Current density, angular momentum, Bessel function, moment of inertia, polar moment of inertia of the section, internal quantum number, rotational quantum number, luminous intensity, J/ψ meson | |
Imaginary unit, current density, unit vector, internal quantum number, 4-vector current density | |
Kaons (eng. kaons), thermodynamic equilibrium constant, coefficient of electronic thermal conductivity of metals, modulus of uniform compression, mechanical impulse, Josephson constant | |
Coefficient (German: Koeffizient), Boltzmann constant, thermal conductivity, wave number, unit vector | |
Momentum, inductance, Lagrangian function, classical Langevin function, Lorenz number, sound pressure level, Laguerre polynomials, orbital quantum number, energy brightness, brightness (eng. luminance) | |
Length, mean free path, orbital quantum number, radiation length | |
Moment of force, magnetization vector, torque, Mach number, mutual inductance, magnetic quantum number, molar mass | |
Mass (lat. massa), magnetic quantum number (eng. magnetic quantum number), magnetic moment (eng. magnetic moment), effective mass, mass defect, Planck mass | |
Quantity (lat. numerus), Avogadro's constant, Debye number, total radiation power, optical instrument magnification, concentration, power | |
Refractive index, amount of matter, normal vector, unit vector, neutron, quantity, fundamental quantum number, rotation frequency, concentration, polytropic index, Loschmidt constant | |
Origin of coordinates (lat. origo) | |
Power (lat. potestas), pressure (lat. pressūra), Legendre polynomials, weight (fr. poids), gravity, probability (lat. probabilitas), polarizability, transition probability, 4-momentum | |
Momentum (lat. petere), proton (eng. proton), dipole moment, wave parameter | |
Electric charge (English quantity of electricity), quantity of heat (English quantity of heat), generalized force, radiation energy, light energy, quality factor (English quality factor), zero Abbe invariant, quadrupole electric moment (English quadrupole moment) , nuclear reaction energy | |
Electric charge, generalized coordinate, quantity of heat, effective charge, quality factor | |
Electrical resistance, gas constant, Rydberg constant, von Klitzing constant, reflectance, resistance, resolution, luminosity, particle path, distance | |
Radius (lat. radius), radius vector, radial polar coordinate, specific heat of phase transition, specific heat of fusion, specific refraction (lat. rēfractiō), distance | |
Surface area, entropy, action, spin, spin quantum number, strangeness, Hamilton's principal function, scattering matrix , evolution operator, Poynting vector | |
Displacement (Italian ь s "postamento), strange quark (English strange quark), path, space-time interval (English spacetime interval), optical path length | |
Temperature (lat. temperātūra), period (lat. tempus), kinetic energy, critical temperature, therm, half-life, critical energy, isospin | |
Time (Latin tempus), true quark, truthfulness, Planck time | |
Internal energy, potential energy, Umov vector, Lennard-Jones potential, Morse potential, 4-speed, electrical voltage | |
Up quark, speed, mobility, specific internal energy, group velocity | |
Volume (French volume), voltage (English voltage), potential energy, visibility of the interference fringe, Verdet constant (English Verdet constant) | |
Velocity (lat. vēlōcitās), phase velocity, specific volume | |
Mechanical work, work function, W boson, energy, binding energy of the atomic nucleus, power | |
Speed, energy density, internal conversion ratio, acceleration | |
Reactance, longitudinal increase | |
Variable, displacement, Cartesian coordinate, molar concentration, anharmonicity constant, distance | |
Hypercharge, force function, linear increase, spherical functions | |
Cartesian coordinate | |
Impedance, Z boson, atomic number or nuclear charge number (German: Ordnungszahl), partition function (German: Zustandssumme), Hertz vector, valence, electrical impedance, angular magnification, characteristic vacuum impedance | |
Cartesian coordinate | |
Thermal expansion coefficient, alpha particles, angle, fine structure constant, angular acceleration, Dirac matrices, expansion coefficient, polarization, heat transfer coefficient, dissociation coefficient, specific thermoelectromotive force, Mach angle, absorption coefficient, natural indicator of light absorption, degree of emissivity of the body, damping constant | |
Angle, beta particles, particle speed divided by the speed of light, quasi-elastic force coefficient, Dirac matrices, isothermal compressibility, adiabatic compressibility, damping coefficient, angular width of interference fringes, angular acceleration | |
Gamma function, Christophel symbols, phase space, adsorption magnitude, velocity circulation, energy level width | |
Angle, Lorentz factor, photon, gamma rays, specific gravity, Pauli matrices, gyromagnetic ratio, thermodynamic pressure coefficient, surface ionization coefficient, Dirac matrices, adiabatic exponent | |
Variation of magnitude (eg), Laplace operator, dispersion, fluctuation, degree of linear polarization, quantum defect | |
Small displacement, Dirac delta function, Kronecker delta | |
Electrical constant, angular acceleration, unit antisymmetric tensor, energy | |
Riemann zeta function | |
Efficiency, dynamic viscosity coefficient, metric Minkowski tensor, internal friction coefficient, viscosity, scattering phase, eta meson | |
Statistical temperature, Curie point, thermodynamic temperature, moment of inertia, Heaviside function | |
Angle to the X axis in the XY plane in spherical and cylindrical coordinate systems, potential temperature, Debye temperature, nutation angle, normal coordinate, wetting measure, Cubbibo angle, Weinberg angle | |
Extinction coefficient, adiabatic index, magnetic susceptibility of the medium, paramagnetic susceptibility | |
Cosmological constant, Baryon, Legendre operator, lambda hyperon, lambda plus hyperon | |
Wavelength, specific heat of fusion, linear density, mean free path, Compton wavelength, operator eigenvalue, Gell-Mann matrices | |
Friction coefficient, dynamic viscosity, magnetic permeability, magnetic constant, chemical potential, Bohr magneton, muon, erected mass, molar mass, Poisson's ratio, nuclear magneton | |
Frequency, neutrino, kinematic viscosity coefficient, stoichiometric coefficient, amount of matter, Larmor frequency, vibrational quantum number | |
Grand canonical ensemble, xi-null-hyperon, xi-minus-hyperon | |
Coherence length, Darcy coefficient | |
Product, Peltier coefficient, Poynting vector | |
3.14159…, pi-bond, pi-plus meson, pi-zero meson | |
Resistivity, density, charge density, radius in polar coordinate system, spherical and cylindrical coordinate systems, density matrix, probability density | |
Summation operator, sigma-plus-hyperon, sigma-zero-hyperon, sigma-minus-hyperon | |
Electrical conductivity, mechanical stress (measured in Pa), Stefan-Boltzmann constant, surface density, reaction cross section, sigma coupling, sector velocity, surface tension coefficient, specific photoconductivity, differential scattering cross section, screening constant, thickness | |
Lifetime, tau lepton, time interval, lifetime, period, linear charge density, Thomson coefficient, coherence time, Pauli matrix, tangential vector | |
Y boson | |
Magnetic flux, electric displacement flux, work function, ide, Rayleigh dissipative function, Gibbs free energy, wave energy flux, lens optical power, radiation flux, luminous flux, magnetic flux quantum | |
Angle, electrostatic potential, phase, wave function, angle, gravitational potential, function, Golden ratio, mass force field potential | |
X boson | |
Rabi frequency, thermal diffusivity, dielectric susceptibility, spin wave function | |
Wave function, interference aperture | |
Wave function, function, current function | |
Ohm, solid angle, number of possible states of a statistical system, omega-minus-hyperon, angular velocity of precession, molecular refraction, cyclic frequency | |
Angular frequency, meson, state probability, Larmor frequency of precession, Bohr frequency, solid angle, flow velocity |
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Magnitude | Designation | SI unit of measurement | |
Current strength | I | ampere | A |
Current Density | j | ampere per square meter | A/m2 |
Electric charge | Q, q | pendant | Cl |
Electric dipole moment | p | coulomb meter | Cl ∙ m |
Polarization | P | pendant per square meter | C/m2 |
Voltage, potential, EMF | U, φ, ε | volt | IN |
Electric field strength | E | volt per meter | V/m |
Electrical capacity | C | farad | F |
Electrical resistance | R, r | ohm | Ohm |
Electrical resistivity | ρ | ohm meter | Ohm ∙ m |
Electrical conductivity | G | Siemens | Cm |
Magnetic induction | B | tesla | Tl |
Magnetic flux | F | weber | Wb |
Magnetic field strength | H | ampere per meter | Vehicle |
Magnetic moment | pm | ampere square meter | A ∙ m2 |
Magnetization | J | ampere per meter | Vehicle |
Inductance | L | Henry | Gn |
Electromagnetic energy | N | joule | J |
Volumetric energy density | w | joule per cubic meter | J/m3 |
Active power | P | watt | W |
Reactive power | Q | var | var |
Full power | S | watt-ampere | W∙A |
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Physical quantities of electric current
Hello, dear readers of our site! We continue the series of articles dedicated to novice electricians. Today we will briefly look at the physical quantities of electric current, types of connections and Ohm's law.
First, let's remember what types of current exist:
Alternating current (letter designation AC) - is generated due to the magnetic effect. This is the same current that you and I have in our homes. It does not have any poles because it changes them many times per second. This phenomenon (change of polarities) is called frequency, it is expressed in hertz (Hz). Currently, our network uses an alternating current of 50 Hz (that is, a change in direction occurs 50 times per second). The two wires that enter the home are called phase and neutral, since there are no poles.
Direct current (letter designation DC) is the current that is obtained chemically (for example, batteries, accumulators). It is polarized and flows in a certain direction.
Basic physical quantities:
- Potential difference (symbol U). Since generators act on electrons like a water pump, there is a difference across its terminals, which is called a potential difference. It is expressed in volts (designation B). If you and I measure the potential difference at the input and output connections of an electrical appliance with a voltmeter, we will see a reading of 230-240 V. Usually this value is called voltage.
- Current strength (designation I). Let's say when a lamp is connected to a generator, an electrical circuit is created that passes through the lamp. A stream of electrons flows through the wires and through the lamp. The strength of this flow is expressed in amperes (symbol A).
- Resistance (designation R). Resistance usually refers to the material that allows electrical energy to be converted into heat. Resistance is expressed in ohms (symbol Ohm). Here we can add the following: if the resistance increases, then the current decreases, since the voltage remains constant, and vice versa, if the resistance decreases, the current increases.
- Power (designation P). Expressed in watts (symbol W), it determines the amount of energy consumed by the appliance that is currently connected to your outlet.
Types of consumer connections
Conductors, when included in a circuit, can be connected to each other in various ways:
- Consistently.
- Parallel.
- Mixed method
A serial connection is a connection in which the end of the previous conductor is connected to the beginning of the next one.
A parallel connection is a connection in which all the beginnings of the conductors are connected at one point, and the ends at another.
A mixed connection of conductors is a combination of series and parallel connections. Everything we have told in this article is based on the basic law of electrical engineering - Ohm's law, which states that the current strength in a conductor is directly proportional to the applied voltage at its ends and inversely proportional to the resistance of the conductor.
In the form of a formula, this law is expressed as follows:
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