Physical quantities

Physical quantity– this is a characteristic of physical objects or phenomena of the material world, common to many objects or phenomena in qualitative terms, but individual in quantitative terms for each of them. For example, mass, length, area, temperature, etc.

Each physical quantity has its own qualitative and quantitative characteristics .

Qualitative characteristic is determined by what property of a material object or what feature of the material world this value characterizes. Thus, the property "strength" quantitatively characterizes such materials as steel, wood, fabric, glass and many others, while the quantitative value of strength for each of them is completely different.

To identify a quantitative difference in the content of a property in any object, displayed by a physical quantity, the concept is introduced the size of a physical quantity . This size is set during measurements- a set of operations performed to determine the quantitative value of a quantity (FZ "On ensuring the uniformity of measurements"

The purpose of measurements is to determine the value of a physical quantity - a certain number of units adopted for it (for example, the result of measuring the mass of a product is 2 kg, the height of a building is 12 m, etc.). Between the sizes of each physical quantity there are relations in the form of numerical forms (such as "greater than", "less than", "equality", "sum", etc.), which can serve as a model of this quantity.

Depending on the degree of approximation to objectivity, there are true, actual and measured values ​​of a physical quantity .

The true value of a physical quantity - this value, ideally reflecting in qualitative and quantitative terms the corresponding property of the object. Due to the imperfection of the means and methods of measurement, the true values ​​of the quantities cannot practically be obtained. They can only be imagined theoretically. And the values ​​of the quantity obtained during the measurement, only to a greater or lesser extent approach the true value.

The actual value of the physical quantity - it is the value of a quantity found experimentally and so close to the true value that it can be used instead of it for this purpose.

Measured value of a physical quantity - this is the value obtained during the measurement using specific methods and measuring instruments.

When planning measurements, one should strive to ensure that the range of measured quantities meets the requirements of the measurement task (for example, when monitoring, the measured quantities should reflect the relevant indicators of product quality).

For each product parameter, the following requirements must be met:

The correctness of the wording of the measured value, excluding the possibility of different interpretations (for example, it is necessary to clearly define in which cases the “mass” or “weight” of the product, the “volume” or “capacity” of the vessel, etc.) are determined;

The certainty of the properties of the object to be measured (for example, "the temperature in the room is not more than ... ° C" allows for different interpretations. It is necessary to change the wording of the requirement in such a way that it is clear whether this requirement is established for the maximum or average temperature of the room, which will be in further taken into account when performing measurements);

Use of standardized terms.

Physical units

A physical quantity, which by definition is assigned a numerical value equal to one, is called unit of physical quantity.

Many units of physical quantities are reproduced by the measures used for measurements (for example, meter, kilogram). In the early stages of the development of material culture (in slave-owning and feudal societies), there were units for a small range of physical quantities - length, mass, time, area, volume. Units of physical quantities were chosen without connection with each other, and, moreover, different in different countries and geographical areas. So a large number of often identical in name, but different in size units - cubits, feet, pounds - arose.

With the expansion of trade relations between peoples and the development of science and technology, the number of units of physical quantities increased and the need for unification of units and the creation of systems of units was increasingly felt. On units of physical quantities and their systems began to conclude special international agreements. In the 18th century In France, the metric system of measures was proposed, which later received international recognition. On its basis, a number of metric systems of units were built. Currently, there is a further streamlining of units of physical quantities on the basis of the International System of Units (SI).

Units of physical quantities are divided into systemic, i.e., units included in any system, and non-system units (for example, mm Hg, horsepower, electron volts).

System units physical quantities are divided into main, chosen arbitrarily (meter, kilogram, second, etc.), and derivatives, formed according to the equations of connection between quantities (meter per second, kilogram per cubic meter, newton, joule, watt, etc.).

For the convenience of expressing quantities that are many times larger or smaller than units of physical quantities, we use multiple units (for example, kilometer - 10 3 m, kilowatt - 10 3 W) and submultiples (for example, a millimeter is 10 -3 m, a millisecond is 10-3 s)..

In metric systems of units, multiple and unit units of physical quantities (with the exception of units of time and angle) are formed by multiplying the system unit by 10 n, where n is a positive or negative integer. Each of these numbers corresponds to one of the decimal prefixes used to form multiples and divisional units.

In 1960, at the XI General Conference on Weights and Measures of the International Organization of Weights and Measures (MOMV), the International System was adopted units(SI).

Basic units in the international system of units are: meter (m) - length, kilogram (kg) - mass, second (s) - time, ampere (A) - the strength of the electric current, kelvin (K) – thermodynamic temperature, candela (cd) - light intensity, mole - amount of substance.

Along with systems of physical quantities, so-called off-system units are still used in measurement practice. These include, for example: units of pressure - atmosphere, millimeter of mercury column, unit of length - angstrom, unit of heat - calorie, units of acoustic quantities - decibel, background, octave, units of time - minute and hour, etc. However, in currently there is a tendency to reduce them to a minimum.

The international system of units has a number of advantages: universality, unification of units for all types of measurements, coherence (consistency) of the system (proportionality coefficients in physical equations are dimensionless), better mutual understanding between various specialists in the process of scientific, technical and economic relations between countries.

Currently, the use of units of physical quantities in Russia is legalized by the Constitution of the Russian Federation (Article 71) (standards, standards, the metric system and time calculation are under the jurisdiction of the Russian Federation) and the federal law "On Ensuring the Uniformity of Measurements". Article 6 of the Law determines the use in the Russian Federation of units of the International System of Units adopted by the General Conference on Weights and Measures and recommended for use by the International Organization of Legal Metrology. At the same time, in the Russian Federation, non-systemic units of quantities, the name, designations, rules for writing and using which are established by the Government of the Russian Federation, may be allowed to be used along with SI units of quantities.

In practice, one should be guided by the units of physical quantities regulated by GOST 8.417-2002 “State system for ensuring the uniformity of measurements. Units of values.

Standard along with mandatory application basic and derivative units of the International System of Units, as well as decimal multiples and submultiples of these units, it is allowed to use some units that are not included in the SI, their combinations with SI units, as well as some decimal multiples and submultiples of the listed units that are widely used in practice.

The standard defines the rules for the formation of names and symbols for decimal multiples and submultiples of SI units using multipliers (from 10 -24 to 10 24) and prefixes, rules for writing unit designations, rules for the formation of coherent derived SI units

The multipliers and prefixes used to form the names and symbols of decimal multiples and submultiples of the SI units are given in Table.

Multipliers and prefixes used to form the names and symbols of decimal multiples and submultiples of SI units

Decimal multiplier	Prefix	Prefix designation	Decimal multiplier	Prefix	Prefix designation
int.	rus	int.	russ
10 24	yotta	Y	And	10 –1	deci	d	d
10 21	zetta	Z	W	10 –2	centi	c	with
10 18	exa	E	E	10 –3	Milli	m	m
10 15	peta	P	P	10 –6	micro	µ	mk
10 12	tera	T	T	10 –9	nano	n	n
10 9	giga	G	G	10 –12	pico	p	P
10 6	mega	M	M	10 –15	femto	f	f
10 3	kilo	k	to	10 –18	atto	a	a
10 2	hecto	h	G	10 –21	zepto	z	h
10 1	soundboard	da	Yes	10 –24	yokto	y	and

Coherent derived units The international system of units, as a rule, is formed using the simplest equations of connection between quantities (defining equations), in which the numerical coefficients are equal to 1. To form derived units, the designations of quantities in the connection equations are replaced by the designations of SI units.

If the connection equation contains a numerical coefficient other than 1, then to form a coherent derivative of the SI unit, the designations of quantities with values ​​in SI units are substituted on the right side, giving, after multiplication by the coefficient, a total numerical value equal to 1.

Physics, as a science that studies natural phenomena, uses a standard research methodology. The main stages can be called: observation, putting forward a hypothesis, conducting an experiment, substantiating a theory. In the course of observation, the distinctive features of the phenomenon, the course of its course, possible causes and consequences are established. The hypothesis allows you to explain the course of the phenomenon, to establish its patterns. The experiment confirms (or does not confirm) the validity of the hypothesis. Allows you to set the quantitative ratio of values ​​in the course of the experiment, which leads to an accurate establishment of dependencies. The hypothesis confirmed in the course of the experiment forms the basis of a scientific theory.

No theory can claim to be reliable if it has not received full and unconditional confirmation during the experiment. Carrying out the latter is associated with measurements of physical quantities characterizing the process. is the basis of measurements.

What it is

Measurement refers to those quantities that confirm the validity of the hypothesis of regularities. A physical quantity is a scientific characteristic of a physical body, the qualitative ratio of which is common to many similar bodies. For each body, such a quantitative characteristic is purely individual.

If we turn to the special literature, then in the reference book by M. Yudin et al. (1989 edition) we read that a physical quantity is: “a characteristic of one of the properties of a physical object (physical system, phenomenon or process), which is qualitatively common for many physical objects, but quantitatively individual for each object.

Ozhegov's Dictionary (1990 edition) claims that a physical quantity is "the size, volume, length of an object."

For example, length is a physical quantity. Mechanics interprets the length as the distance traveled, electrodynamics uses the length of the wire, in thermodynamics a similar value determines the thickness of the walls of the vessels. The essence of the concept does not change: the units of quantities can be the same, but the value can be different.

A distinctive feature of a physical quantity, say, from a mathematical one, is the presence of a unit of measurement. Meter, foot, arshin are examples of length units.

Units

To measure a physical quantity, it should be compared with a quantity taken as a unit. Remember the wonderful cartoon "Forty-Eight Parrots". To determine the length of the boa constrictor, the heroes measured its length either in parrots, or in elephants, or in monkeys. In this case, the length of the boa constrictor was compared with the height of other cartoon characters. The result quantitatively depended on the standard.

Values ​​- a measure of its measurement in a certain system of units. The confusion in these measures arises not only because of the imperfection and heterogeneity of the measures, but sometimes also because of the relativity of the units.

Russian measure of length - arshin - the distance between the index and thumb fingers. However, the hands of all people are different, and the arshin measured by the hand of an adult man differs from the arshin on the hand of a child or a woman. The same discrepancy between measures of length applies to the fathom (the distance between the tips of the fingers of the arms spread apart) and the elbow (the distance from the middle finger to the elbow of the hand).

It is interesting that men of small stature were taken into the shops as clerks. Cunning merchants saved fabric with the help of several smaller measures: arshin, cubit, fathom.

Systems of measures

Such a variety of measures existed not only in Russia, but also in other countries. The introduction of units of measurement was often arbitrary, sometimes these units were introduced only because of the convenience of their measurement. For example, to measure atmospheric pressure, mm Hg was entered. The famous one, which used a tube filled with mercury, allowed such an unusual value to be introduced.

Engine power was compared with (which is practiced in our time).

Various physical quantities made the measurement of physical quantities not only difficult and unreliable, but also complicating the development of science.

Unified system of measures

A unified system of physical quantities, convenient and optimized in every industrialized country, has become an urgent need. The idea of ​​choosing as few units as possible was adopted as a basis, with the help of which other quantities could be expressed in mathematical relations. Such basic quantities should not be related to each other, their meaning is determined unambiguously and clearly in any economic system.

Various countries have tried to solve this problem. The creation of a unified GHS, ISS and others) was undertaken repeatedly, but these systems were inconvenient either from a scientific point of view, or in domestic, industrial use.

The task, set at the end of the 19th century, was solved only in 1958. A unified system was presented at the meeting of the International Committee of Legal Metrology.

Unified system of measures

The year 1960 was marked by the historic meeting of the General Conference on Weights and Measures. A unique system called "Systeme internationale d" units "(abbreviated as SI) was adopted by the decision of this honorary meeting. In the Russian version, this system is called System International (abbreviation SI).

7 basic units and 2 additional units are taken as a basis. Their numerical value is determined in the form of a standard

Table of physical quantities SI

Name of the main unit	Measured value	Designation
		international	Russian
Basic units
kilogram
	Current strength
	Temperature
	Amount of substance
	The power of light
Additional units
	flat corner
Steradian	Solid angle

The system itself cannot consist of only seven units, since the variety of physical processes in nature requires the introduction of more and more new quantities. The structure itself provides for not only the introduction of new units, but also their relationship in the form of mathematical relationships (they are often called dimension formulas).

The unit of a physical quantity is obtained by multiplying and dividing the basic units in the dimension formula. The absence of numerical coefficients in such equations makes the system not only convenient in all respects, but also coherent (consistent).

Derived units

Units of measurement, which are formed from the seven basic ones, are called derivatives. In addition to the basic and derived units, it became necessary to introduce additional ones (radians and steradians). Their dimension is considered to be zero. The lack of measuring instruments for their determination makes it impossible to measure them. Their introduction is due to the use in theoretical studies. For example, the physical quantity "force" in this system is measured in newtons. Since force is a measure of the mutual action of bodies on each other, which is the cause of varying the speed of a body of a certain mass, it can be defined as the product of a unit of mass per unit of speed divided by a unit of time:

F = k٠M٠v/T, where k is the proportionality factor, M is the unit of mass, v is the unit of speed, T is the unit of time.

The SI gives the following formula for dimensions: H = kg * m / s 2, where three units are used. And the kilogram, and the meter, and the second are classified as basic. The proportionality factor is 1.

It is possible to introduce dimensionless quantities, which are defined as a ratio of homogeneous quantities. These include, as is known, equal to the ratio of the friction force to the force of normal pressure.

Table of physical quantities derived from the main ones

Unit name	Measured value	Dimensions formula
		kg٠m 2 ٠s -2
	pressure	kg٠ m -1 ٠s -2
	magnetic induction	kg ٠А -1 ٠с -2
	electrical voltage	kg ٠m 2 ٠s -3 ٠A -1
	Electrical resistance	kg ٠m 2 ٠s -3 ٠A -2
	Electric charge
	power	kg ٠m 2 ٠s -3
	Electrical capacitance	m -2 ٠kg -1 ٠c 4 ٠A 2
Joule per Kelvin	Heat capacity	kg ٠m 2 ٠s -2 ٠K -1
becquerel	The activity of a radioactive substance
	magnetic flux	m 2 ٠kg ٠s -2 ٠A -1
	Inductance	m 2 ٠kg ٠s -2 ٠А -2
	Absorbed dose
	Equivalent radiation dose
	illumination	m -2 ٠cd ٠sr -2
	Light flow
	Strength, weight	m ٠kg ٠s -2
	electrical conductivity	m -2 ٠kg -1 ٠s 3 ٠А 2
	Electrical capacitance	m -2 ٠kg -1 ٠c 4 ٠A 2

Off-system units

The use of historically established values ​​that are not included in the SI or differ only by a numerical coefficient is allowed when measuring values. These are non-systemic units. For example, mmHg, X-ray and others.

Numeric coefficients are used to introduce submultiples and multiples. Prefixes correspond to a certain number. An example is centi-, kilo-, deca-, mega- and many others.

1 kilometer = 1000 meters,

1 centimeter = 0.01 meters.

Typology of values

Let's try to point out a few basic features that allow you to set the type of value.

1. Direction. If the action of a physical quantity is directly related to the direction, it is called vector, others are called scalar.

2. The presence of dimension. The existence of a formula for physical quantities makes it possible to call them dimensional. If in the formula all units have a zero degree, then they are called dimensionless. It would be more correct to call them quantities with a dimension equal to 1. After all, the concept of a dimensionless quantity is illogical. The main property - dimension - has not been canceled!

3. If possible, addition. An additive quantity whose value can be added, subtracted, multiplied by a coefficient, etc. (for example, mass) is a physical quantity that is summable.

4. In relation to the physical system. Extensive - if its value can be composed of the values ​​of the subsystem. An example is the area measured in square meters. Intensive - a quantity whose value does not depend on the system. These include temperature.

Consider a physical record m=4kg. In this formula "m"- designation of physical quantity (mass), "4" - numerical value or magnitude, "kg"- unit of measurement of a given physical quantity.

The values ​​are of different kinds. Here are two examples:
1) The distance between points, the lengths of segments, broken lines - these are quantities of the same kind. They are expressed in centimeters, meters, kilometers, etc.
2) The durations of time intervals are also quantities of the same kind. They are expressed in seconds, minutes, hours, etc.

Quantities of the same kind can be compared and added:

BUT! It is pointless to ask which is greater: 1 meter or 1 hour, and you cannot add 1 meter to 30 seconds. The duration of time intervals and distance are quantities of various kinds. They cannot be compared or combined.

Values ​​can be multiplied by positive numbers and zero.

Taking any value e per unit of measurement, it can be used to measure any other quantity a the same kind. As a result of the measurement, we get that a=x e, where x is a number. This number x is called the numerical value of the quantity a with unit of measure e.

There are dimensionless physical quantities. They do not have units of measurement, that is, they are not measured in anything. For example, the coefficient of friction.

What is SI?

According to Professor Peter Kampson and Dr. Naoko Sano of Newcastle University, published in the journal Metrology (Metrology), the kilogram standard adds an average of about 50 micrograms per hundred years, which can ultimately affect very many physical quantities.

The kilogram is the only SI unit that is still defined using a standard. All other measures (meter, second, degree, ampere, etc.) can be determined with the required accuracy in a physical laboratory. The kilogram is included in the definition of other quantities, for example, the unit of force is the newton, which is defined as the force that changes the speed of a 1 kg body by 1 m/s in the direction of the force in 1 second. Other physical quantities depend on the Newton value, so that in the end the chain can lead to a change in the value of many physical units.

The most important kilogram is a cylinder with a diameter and a height of 39 mm, consisting of an alloy of platinum and iridium (90% platinum and 10% iridium). It was cast in 1889 and is stored in a safe at the International Bureau of Weights and Measures in the city of Sèvres near Paris. The kilogram was originally defined as the mass of one cubic decimeter (liter) of pure water at 4°C and standard atmospheric pressure at sea level.

Initially, 40 exact copies were made from the kilogram standard, which were sold all over the world. Two of them are located in Russia, at the All-Russian Research Institute of Metrology. Mendeleev. Later, another series of replicas was cast. Platinum was chosen as the base material for the reference because of its high oxidation resistance, high density, and low magnetic susceptibility. The standard and its replicas are used to standardize the mass in a wide variety of industries. Including where micrograms are essential.

Physicists believe that the fluctuations in weight were the result of atmospheric pollution and changes in the chemical composition in the surface of the cylinders. Despite the fact that the standard and its replicas are stored in special conditions, this does not save the metal from interacting with the environment. The exact weight of a kilogram was determined using X-ray photoelectron spectroscopy. It turned out that the kilogram “recovered” by almost 100 mcg.

At the same time, copies of the standard from the very beginning differed from the original and their weight also changes in different ways. So, the main American kilogram initially weighed 39 micrograms less than the standard, and a check in 1948 showed that it had increased by 20 micrograms. Another American copy, on the contrary, is losing weight. In 1889, the kilogram number 4 (K4) weighed 75 micrograms less than the standard, and in 1989 already 106.

In science and technology, units of measurement of physical quantities are used, forming certain systems. The set of units established by the standard for mandatory use is based on the units of the International System (SI). In the theoretical branches of physics, units of the CGS systems are widely used: CGSE, CGSM and the symmetric Gaussian CGS system. Units of the technical system of the ICSC and some off-system units also find some use.

The international system (SI) is built on 6 basic units (meter, kilogram, second, kelvin, ampere, candela) and 2 additional ones (radian, steradian). In the final version of the draft standard "Units of Physical Quantities" are given: units of the SI system; units allowed for use on a par with SI units, for example: ton, minute, hour, degree Celsius, degree, minute, second, liter, kilowatt-hour, revolution per second, revolution per minute; units of the CGS system and other units used in theoretical sections of physics and astronomy: light year, parsec, barn, electron volt; units temporarily allowed for use such as: angstrom, kilogram-force, kilogram-force-meter, kilogram-force per square centimeter, millimeter of mercury, horsepower, calorie, kilocalorie, roentgen, curie. The most important of these units and the ratios between them are given in Table P1.

The abbreviations of units given in the tables are used only after the numerical value of the quantity or in the headings of the columns of the tables. You cannot use abbreviations instead of the full names of units in the text without the numerical value of the quantities. When using both Russian and international unit designations, a roman font is used; designations (abbreviated) of units whose names are given by the names of scientists (newton, pascal, watt, etc.) should be written with a capital letter (N, Pa, W); in the notation of units, the dot as a sign of reduction is not used. The designations of the units included in the product are separated by dots as multiplication signs; a slash is usually used as a division sign; if the denominator includes a product of units, then it is enclosed in brackets.

For the formation of multiples and submultiples, decimal prefixes are used (see Table P2). The use of prefixes, which are a power of 10 with an indicator that is a multiple of three, is especially recommended. It is advisable to use submultiples and multiples of units derived from SI units and resulting in numerical values ​​between 0.1 and 1000 (for example: 17,000 Pa should be written as 17 kPa).

It is not allowed to attach two or more prefixes to one unit (for example: 10 -9 m should be written as 1 nm). To form mass units, a prefix is ​​attached to the main name “gram” (for example: 10 -6 kg = = 10 -3 g = 1 mg). If the complex name of the original unit is a product or a fraction, then the prefix is ​​\u200b\u200battached to the name of the first unit (for example, kN∙m). In necessary cases, it is allowed to use submultiple units of length, area and volume (for example, V / cm) in the denominator.

Table P3 shows the main physical and astronomical constants.

Table P1

UNITS OF PHYSICAL MEASUREMENTS IN THE SI SYSTEM

AND THEIR RELATION WITH OTHER UNITS

Name of quantities	Units	Abbreviation	The size	Coefficient for conversion to SI units
GHS	ICSU and non-systemic units
Basic units
Length	meter	m		1 cm=10 -2 m	1 Å \u003d 10 -10 m 1 light year \u003d 9.46 × 10 15 m
Weight	kg	kg		1g=10 -3 kg
Time	second	with			1 h=3600 s 1 min=60 s
Temperature	kelvin	To			1 0 C=1 K
Current strength	ampere	BUT		1 SGSE I \u003d \u003d 1 / 3 × 10 -9 A 1 SGSM I \u003d 10 A
The power of light	candela	cd
Additional units
flat corner	radian	glad			1 0 \u003d p / 180 rad 1¢ \u003d p / 108 × 10 -2 rad 1² \u003d p / 648 × 10 -3 rad
Solid angle	steradian	Wed			Full solid angle=4p sr
Derived units
Frequency	hertz	Hz	s -1

Continuation of Table P1

Angular velocity	radians per second	rad/s	s -1		1 rpm=2p rad/s 1 rpm==0.105 rad/s
Volume	cubic meter	m 3	m 3	1cm 2 \u003d 10 -6 m 3	1 l \u003d 10 -3 m 3
Speed	meters per second	m/s	m×s –1	1cm/s=10 -2 m/s	1km/h=0.278m/s
Density	kilogram per cubic meter	kg / m 3	kg×m -3	1g / cm 3 \u003d \u003d 10 3 kg / m 3
Force	newton	H	kg×m×s –2	1 dyne = 10 -5 N	1 kg=9.81N
Work, energy, amount of heat	joule	J (N×m)	kg × m 2 × s -2	1 erg \u003d 10 -7 J	1 kgf×m=9.81 J 1 eV=1.6×10 –19 J 1 kW×h=3.6×10 6 J 1 cal=4.19 J 1 kcal=4.19×10 3 J
Power	watt	W (J/s)	kg × m 2 × s -3	1erg/s=10 -7 W	1hp=735W
Pressure	pascal	Pa (N / m 2)	kg∙m –1 ∙s –2	1 din / cm 2 \u003d 0.1 Pa	1 atm \u003d 1 kgf / cm 2 \u003d \u003d \u003d 0.981 ∙ 10 5 Pa 1 mm Hg \u003d 133 Pa 1 atm \u003d \u003d 760 mm Hg \u003d \u003d 1.013 10 5 Pa
Moment of power	newton meter	N∙m	kgm 2 ×s -2	1 dyne cm = = 10 –7 N × m	1 kgf×m=9.81 N×m
Moment of inertia	kilogram square meter	kg × m 2	kg × m 2	1 g × cm 2 \u003d \u003d 10 -7 kg × m 2
Dynamic viscosity	pascal second	Pa×s	kg×m –1 ×s –1	1P / poise / \u003d \u003d 0.1 Pa × s

Continuation of Table P1

Kinematic viscosity	square meter per second	m 2 /s	m 2 × s -1	1St / stokes / \u003d \u003d 10 -4 m 2 / s
Heat capacity of the system	joule per kelvin	J/K	kg×m 2 x x s –2 ×K –1		1 cal / 0 C = 4.19 J / K
Specific heat	joule per kilogram kelvin	J/ (kg×K)	m 2 × s -2 × K -1		1 kcal / (kg × 0 C) \u003d \u003d 4.19 × 10 3 J / (kg × K)
Electric charge	pendant	Cl	A×s	1SGSE q = =1/3×10 –9 C 1SGSM q = =10 C
Potential, electrical voltage	volt	V (W/A)	kg×m 2 x x s –3 ×A –1	1SGSE u = =300 V 1SGSM u = =10 –8 V
Electric field strength	volt per meter	V/m	kg×m x x s –3 ×A –1	1 SGSE E \u003d \u003d 3 × 10 4 V / m
Electrical displacement (electrical induction)	pendant per square meter	C/m 2	m –2 ×s×A	1SGSE D \u003d \u003d 1 / 12p x x 10 -5 C / m 2
Electrical resistance	ohm	Ohm (V/A)	kg × m 2 × s -3 x x A -2	1SGSE R = 9×10 11 Ohm 1SGSM R = 10 –9 Ohm
Electrical capacitance	farad	F (C/V)	kg -1 ×m -2 x s 4 ×A 2	1SGSE C \u003d 1 cm \u003d \u003d 1 / 9 × 10 -11 F

End of table P1

magnetic flux	weber	Wb (W×s)	kg × m 2 × s -2 x x A -1	1SGSM f = =1 μs (maxwell) = =10 –8 Wb
Magnetic induction	tesla	T (Wb / m 2)	kg×s –2 ×A –1	1SGSM B = =1 Gs (gauss) = =10 –4 T
Magnetic field strength	ampere per meter	A/m	m –1 ×A	1SGSM H \u003d \u003d 1E (oersted) \u003d \u003d 1 / 4p × 10 3 A / m
Magnetomotive force	ampere	BUT	BUT	1SGSM Fm
Inductance	Henry	Hn (Wb/A)	kg×m 2 x x s –2 ×A –2	1SGSM L \u003d 1 cm \u003d \u003d 10 -9 H
Light flow	lumen	lm	cd
Brightness	candela per square meter	cd/m2	m–2 ×cd
illumination	luxury	OK	m–2 ×cd