What does the letter e stand for in physics. Designation: height, width, length. Width - designation by letter. Width designation on drawings. Units not included in si

11.02.2024

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 standards for design documentation 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.

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List of notations in physics is... What is List of notations in physics?

The list of notations in physics includes notation of concepts in physics from school and university courses. General mathematical concepts and operations are also included to make a complete reading of the physical formulas possible.

Since the number of physical quantities is greater than the number of letters in the Latin and Greek alphabets, the same letters are used to represent different quantities. For some physical quantities, several notations are accepted (for example, for

and others) to prevent confusion with other quantities in this branch of physics.

In printed text, mathematical notations using the Latin alphabet are usually written in italics. The names of functions, as well as numbers and Greek letters, are left straight. Letters may also be written in different fonts to distinguish the nature of quantities or mathematical operations. In particular, it is customary to denote vector quantities in bold, and tensor quantities in bold. Sometimes a Gothic font is also used for designation. Intensive quantities are usually indicated in lowercase letters, and extensive quantities in capital letters.

For historical reasons, many of the designations use Latin letters - from the first letter of the word denoting the concept in a foreign language (mainly Latin, English, French and German). When such a connection exists, it is indicated in parentheses. Among Latin letters, letters are practically not used to denote physical quantities.

Symbol Meaning and Origin

To designate some quantities, several letters or individual words or abbreviations are sometimes used. Thus, a constant value in a formula is often denoted as const. A differential is denoted by a small letter d before the name of the quantity, for example dx.

Latin names for mathematical functions and operations that are often used in physics:

Large Greek letters, which are similar in writing to Latin ones (), are used very rarely.

Symbol Meaning

Cyrillic letters are now very rarely used to denote physical quantities, although they were partially used in the Russian-speaking scientific tradition. One example of the use of a Cyrillic letter in modern international scientific literature is the designation of the Lagrange invariant by the letter Z. The Dirac comb is sometimes denoted by the letter Ш, since the graph of the function is visually similar to the shape of the letter.

One or more variables on which the physical quantity depends are indicated in parentheses. For example, f(x, y) means that the quantity f is a function of x and y.

Diacritics are added to the symbol of a physical quantity to indicate certain differences. Below, diacric marks have been added to the letter x as an example.

Designations of physical quantities often have a lower, upper, or both subscript. Typically, the subscript denotes a characteristic feature of a quantity, for example, its serial number, type, projection, etc. The superscript denotes a degree, except when the quantity is a tensor.

To visually indicate physical processes and mathematical operations, graphical notations are used: Feynman diagrams, spin networks and Penrose graphical notations.

	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), Hertzian vector, valence, electrical impedance, angular magnification, 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

dik.academic.ru

Electricity and magnetism. Units of measurement of physical quantities

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

tutata.ru

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 current 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:

fazaa.ru

Physics and basic physical quantities

Mikhail Vasilyevich Lomonosov introduced the word physics into the Russian language by publishing a textbook translated from German - the first physics textbook in Russia.

length,
weight,
time,
current strength,
temperature,
amount of substance
the power of light.

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.

SI: general information

Conclusion

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. 1449

STATE 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)

By Decree of the USSR State Committee on Standards dated March 19, 1981 No. 1449, the introduction date was established

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
Name	Dimension	Name	international	Definition
Length				A meter is the length of the path traveled by light in a vacuum during a time interval of 1/299792458 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 negligibly 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 for 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 for thermodynamic temperature (for example, T 68 or t 68). 4. The uniformity of light measurements is ensured in accordance with GOST 8.023-83.

(Changed edition, Amendment No. 2, 3). 2.2. Additional SI units are given in table. 2.

table 2

Name of quantity
	Name	Designation	Definition
	Name	international	Definition
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

(Changed edition, Amendment No. 3). 2.3. Derived SI units should be formed from basic and additional SI units according to the rules for the formation of coherent derived units (see mandatory Appendix 1). Derived SI units that have special names can also be used to form other derived SI units. Derived units with special names and examples of other derived units are given in Table. 3 - 5. Note. SI electrical and magnetic units should be formed according to the rationalized form of the electromagnetic field equations.

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
Name	Dimension	Name	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
Name	Dimension	Name	international	Expression in terms of major and minor, SI units
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

(Changed edition, Amendment No. 3).

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
Name	Dimension	Name	international		Expression in terms of SI major and supplementary units
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
	Name	international	Relation to SI unit
Weight
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

(Changed edition, Amendment No. 3).

Table 7

Units temporarily approved for use

Name of quantity				Note
	Name	Designation	Relation to SI unit
	Name	international	Relation to SI unit
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
Rotation frequency	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

(Changed edition, Amendment No. 3).

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
Factor	Console	international	Factor	Console	international

4.2. Attaching two or more prefixes in a row to the name of a unit is not allowed. For example, instead of the name of the unit micromicrofarad, you should write picofarad. Notes: 1 Due to the fact that the name of the basic unit - kilogram - contains the prefix “kilo”, to form multiple and sub-multiple units of mass, the sub-multiple unit of gram (0.001 kg, kg) is used, and the prefixes must be attached to the word “gram”, for example, milligram (mg, mg) instead of microkilogram (m kg, μkg). 2. The submultiple unit of mass - “gram” can be used without attaching a prefix. 4.3. The prefix or its designation should be written together with the name of the unit to which it is attached, or, accordingly, with its designation. 4.4. If a unit is formed as a product or relation of units, the prefix should be attached to the name of the first unit included in the product or relation. It is allowed to use a prefix in the second factor of the product or in the denominator only in justified cases, when such units are widespread and the transition to units formed in accordance with the first part of the paragraph is associated with great difficulties, for example: ton-kilometer (t × km; t × km), watt per square centimeter (W / cm 2; W/cm 2), volt per centimeter (V / cm; V/cm), ampere per square millimeter (A / mm 2; A/mm 2). 4.5. The names of multiples and submultiples of a unit raised to a power should be formed by attaching a prefix to the name of the original unit, for example, to form the names of a multiple or submultiple unit of a unit of area - a square meter, which is the second power of a unit of length - a meter, the prefix should be attached to the name of this last unit: square kilometer, square centimeter, etc. 4.6. Designations of multiples and submultiples of a unit raised to a power should be formed by adding the appropriate exponent to the designation of a multiple or submultiple of that unit, the exponent meaning the exponentiation of a multiple or submultiple unit (together with the prefix). Examples: 1. 5 km 2 = 5(10 3 m) 2 = 5 × 10 6 m 2. 2. 250 cm 3 /s = 250(10 -2 m) 3 /(1 s) = 250 × 10 -6 m 3 /s. 3. 0.002 cm -1 = 0.002(10 -2 m) -1 = 0.002 × 100 m -1 = 0.2 m -1. 4.7. Recommendations for choosing decimal multiples and submultiples are given in Reference Appendix 3.

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

5.7. It is allowed to use unit designations in explanations of quantity designations for formulas. Placing symbols of units on the same line with formulas expressing dependencies between quantities or between their numerical values presented in letter form is not allowed. 5.8. The letter designations of the units included in the product should be separated by dots on the middle line, like multiplication signs*. * In typewritten texts, it is allowed not to raise the period. It is allowed to separate the letter designations of units included in the work with spaces, if this does not lead to misunderstanding. 5.9. In letter designations of unit ratios, only one line should be used as a division sign: oblique or horizontal. It is allowed to use unit designations in the form of a product of unit designations raised to powers (positive and negative)**. ** If for one of the units included in the relation, the designation is set in the form of a negative degree (for example, s -1, m -1, K -1; c -1, m -1, K -1), use an oblique or horizontal line not allowed. 5.10. When using a slash, the unit symbols in the numerator and denominator should be placed on a line, and the product of the unit symbols in the denominator should be enclosed in parentheses. 5.11. When indicating a derived unit consisting of two or more units, it is not allowed to combine letter designations and names of units, i.e. For some units, give designations, and for others, names. Note. It is allowed to use combinations of special characters...°,... ¢,... ¢ ¢, % and o / oo with letter designations of units, for example...°/ s, etc.

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 point

v = 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
	Name	international		Relation to SI unit
Length	angstrom
Length	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)
Tension (mechanical)	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 (exactly)
Length
Angle of rotation				2 p rad = 6.28… rad
Magnetomotive force, magnetic potential difference	ampereturn
Brightness
Square

Amended edition, Rev. No. 3.

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
Name of quantity	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)

(Changed edition, Amendment No. 3).

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.

Cheat sheet with formulas in physics for the Unified State Exam

and more (may be needed for grades 7, 8, 9, 10 and 11).

First, a picture that can be printed in a compact form.

Mechanics