What letter denotes power in physics. 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 quantities.

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Studying physics at school lasts several years. At the same time, students are faced with the problem that the same letters represent completely different quantities. Most often this fact concerns Latin letters. How then to solve problems?

There is no need to be afraid of such a repetition. Scientists tried to introduce them into the notation so that identical letters would not appear in the same formula. Most often, students encounter the Latin n. It can be lowercase or uppercase. Therefore, the question logically arises about what n is in physics, that is, in a certain formula encountered by the student.

What does the capital letter N stand for in physics?

Most often in school courses it occurs when studying mechanics. After all, there it can be immediately in spirit meanings - the power and strength of a normal support reaction. Naturally, these concepts do not overlap, because they are used in different sections of mechanics and are measured in different units. Therefore, you always need to define exactly what n is in physics.

Power is the rate of change of energy in a system. This is a scalar quantity, that is, just a number. Its unit of measurement is the watt (W).

The normal ground reaction force is the force exerted on the body by the support or suspension. In addition to the numerical value, it has a direction, that is, it is a vector quantity. Moreover, it is always perpendicular to the surface on which the external influence is made. The unit of this N is newton (N).

What is N in physics, in addition to the quantities already indicated? It could be:

Avogadro's constant;

magnification of the optical device;

substance concentration;

Debye number;

total radiation power.

What does the lowercase letter n stand for in physics?

The list of names that may be hidden behind it is quite extensive. The notation n in physics is used for the following concepts:

refractive index, and it can be absolute or relative;

neutron - a neutral elementary particle with a mass slightly greater than that of a proton;

rotation frequency (used to replace the Greek letter "nu", since it is very similar to the Latin "ve") - the number of repetitions of revolutions per unit of time, measured in hertz (Hz).

What does n mean in physics, besides the quantities already indicated? It turns out that it hides the fundamental quantum number (quantum physics), concentration and Loschmidt constant (molecular physics). By the way, when calculating the concentration of a substance, you need to know the value, which is also written with the Latin “en”. It will be discussed below.

What physical quantity can be denoted by n and N?

Its name comes from the Latin word numerus, translated as “number”, “quantity”. Therefore, the answer to the question of what n means in physics is quite simple. This is the number of any objects, bodies, particles - everything that is discussed in a certain task.

Moreover, “quantity” is one of the few physical quantities that do not have a unit of measurement. It's just a number, without a name. For example, if the problem involves 10 particles, then n will simply be equal to 10. But if it turns out that the lowercase “en” is already taken, then you have to use a capital letter.

Formulas containing capital N

The first of them determines power, which is equal to the ratio of work to time:

In molecular physics there is such a thing as the chemical amount of a substance. Denoted by the Greek letter "nu". To count it, you should divide the number of particles by Avogadro's number:

By the way, the last value is also denoted by the so popular letter N. Only it always has a subscript - A.

To determine the electric charge, you will need the formula:

Another formula with N in physics - oscillation frequency. To count it, you need to divide their number by time:

The letter “en” appears in the formula for the circulation period:

Formulas containing lowercase n

In a school physics course, this letter is most often associated with the refractive index of a substance. Therefore, it is important to know the formulas with its application.

So, for the absolute refractive index the formula is written as follows:

Here c is the speed of light in a vacuum, v is its speed in a refractive medium.

The formula for the relative refractive index is somewhat more complicated:

n 21 = v 1: v 2 = n 2: n 1,

where n 1 and n 2 are the absolute refractive indices of the first and second medium, v 1 and v 2 are the speeds of the light wave in these substances.

How to find n in physics? A formula will help us with this, which requires knowing the angles of incidence and refraction of the beam, that is, n 21 = sin α: sin γ.

What is n equal to in physics if it is the refractive index?

Typically, tables give values for the absolute refractive indices of various substances. Do not forget that this value depends not only on the properties of the medium, but also on the wavelength. Table values of the refractive index are given for the optical range.

So, it became clear what n is in physics. To avoid any questions, it is worth considering some examples.

Power task

№1. During plowing, the tractor pulls the plow evenly. At the same time, he applies a force of 10 kN. With this movement, it covers 1.2 km within 10 minutes. It is necessary to determine the power it develops.

Converting units to SI. You can start with force, 10 N equals 10,000 N. Then the distance: 1.2 × 1000 = 1200 m. Time left - 10 × 60 = 600 s.

Selection of formulas. As mentioned above, N = A: t. But the task has no meaning for the work. To calculate it, another formula is useful: A = F × S. The final form of the formula for power looks like this: N = (F × S) : t.

Solution. Let's first calculate the work and then the power. Then the first action gives 10,000 × 1,200 = 12,000,000 J. The second action gives 12,000,000: 600 = 20,000 W.

Answer. The tractor power is 20,000 W.

Refractive index problems

№2. The absolute refractive index of glass is 1.5. The speed of light propagation in glass is less than in vacuum. You need to determine how many times.

There is no need to convert data to SI.

When choosing formulas, you need to focus on this one: n = c: v.

Solution. From this formula it is clear that v = c: n. This means that the speed of light in glass is equal to the speed of light in a vacuum divided by the refractive index. That is, it decreases by one and a half times.

Answer. The speed of light propagation in glass is 1.5 times less than in vacuum.

№3. There are two transparent media available. The speed of light in the first of them is 225,000 km/s, in the second it is 25,000 km/s less. A ray of light goes from the first medium to the second. The angle of incidence α is 30º. Calculate the value of the angle of refraction.

Do I need to convert to SI? Speeds are given in non-system units. However, when substituted into formulas, they will be reduced. Therefore, there is no need to convert speeds to m/s.

Selecting the formulas necessary to solve the problem. You will need to use the law of light refraction: n 21 = sin α: sin γ. And also: n = с: v.

Solution. In the first formula, n 21 is the ratio of the two refractive indices of the substances in question, that is, n 2 and n 1. If we write down the second indicated formula for the proposed media, we get the following: n 1 = c: v 1 and n 2 = c: v 2. If we make the ratio of the last two expressions, it turns out that n 21 = v 1: v 2. Substituting it into the formula for the law of refraction, we can derive the following expression for the sine of the refraction angle: sin γ = sin α × (v 2: v 1).

We substitute the values of the indicated speeds and the sine of 30º (equal to 0.5) into the formula, it turns out that the sine of the refraction angle is equal to 0.44. According to the Bradis table, it turns out that the angle γ is equal to 26º.

Answer. The refraction angle is 26º.

Tasks for the circulation period

№4. The blades of a windmill rotate with a period of 5 seconds. Calculate the number of revolutions of these blades in 1 hour.

You only need to convert time to SI units for 1 hour. It will be equal to 3,600 seconds.

Selection of formulas. The period of rotation and the number of revolutions are related by the formula T = t: N.

Solution. From the above formula, the number of revolutions is determined by the ratio of time to period. Thus, N = 3600: 5 = 720.

Answer. The number of revolutions of the mill blades is 720.

№5. An airplane propeller rotates at a frequency of 25 Hz. How long will it take the propeller to make 3,000 revolutions?

All data is given in SI, so there is no need to translate anything.

Required formula: frequency ν = N: t. From it you only need to derive the formula for the unknown time. It is a divisor, so it is supposed to be found by dividing N by ν.

Solution. Dividing 3,000 by 25 gives the number 120. It will be measured in seconds.

Answer. An airplane propeller makes 3000 revolutions in 120 s.

Let's sum it up

When a student encounters a formula containing n or N in a physics problem, he needs deal with two points. The first is from what branch of physics the equality is given. This may be clear from the title in the textbook, reference book, or the words of the teacher. Then you should decide what is hidden behind the many-sided “en”. Moreover, the name of the units of measurement helps with this, if, of course, its value is given. Another option is also allowed: look carefully at the remaining letters in the formula. Perhaps they will turn out to be familiar and will give a hint on the issue at hand.

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?

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Basic physical quantities, their letter designations in physics.

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

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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 ridge 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, a subscript denotes a characteristic feature of a quantity, for example, its serial number, type, projection, etc. A 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

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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

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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: