UDC 389.6 BBK 30.10ya7 K59 Kozlov M.G. Metrology and standardization: Textbook M., St. Petersburg: Publishing House "Petersburg Institute of Printing", 2001. 372 p. 1000 copies

Reviewers: L.A. Konopelko, Doctor of Technical Sciences, Professor V.A. Spaev, Doctor of Technical Sciences, Professor

The book outlines the basics of the system for ensuring the uniformity of measurements, which are currently generally accepted on the territory of the Russian Federation. Metrology and standardization are considered as sciences built on scientific and technical legislation, a system for creating and storing standards of units of physical quantities, a service of standard reference data and a service of standard samples. The book contains information about the principles of creating measuring equipment, which is considered as an object of attention of specialists involved in ensuring the uniformity of measurements. Measuring equipment is categorized by types of measurement, based on the standards of the basic units of the SI system. The main provisions of the standardization and certification service in the Russian Federation are considered.

Recommended by UMO as a textbook for specialties: 281400 - "Technology of printing production", 170800 - "Automated printing equipment", 220200 - "Automated information processing and control systems"

The original layout was prepared by the publishing house "Petersburg Institute of Printing"

ISBN 5-93422-014-4

© M.G. Kozlov, 2001. © N.A. Aksinenko, design, 2001. © Publishing house "Petersburg Institute of Press", 2001.

http://www.hi-edu.ru/e-books/xbook109/01/index.html?part-002.htm

Foreword Part I. METROLOGY 1. Introduction to metrology 1.1. Historical aspects of metrology 1.2. Basic concepts and categories of metrology 1.3. Principles of constructing systems of units of physical quantities 1.4. Reproduction and transmission of the size of units of physical quantities. Standards and exemplary measuring instruments 1.5. Measuring instruments and installations 1.6. Measures in metrology and measuring technology. Verification of measuring instruments 1.7. Physical constants and standard reference data 1.8. Standardization in ensuring the uniformity of measurements. Metrological dictionary 2. Basics of building systems of units of physical quantities 2.1. Systems of units of physical quantities 2.2. Dimension formulas 2.3. Basic units of the SI system 2.4. The SI unit of length is the meter 2.5. The SI unit of time is the second 2.6. SI temperature unit - Kelvin 2.7. The SI unit of electric current is Ampere 2.8. Implementation of the basic unit of the SI system - the unit of luminous intensity - candela 2.9. The SI unit of mass is kilogram 2.10. The SI unit of the amount of a substance is the mole 3. Estimation of errors in measurement results 3.1. Introduction 3.2. Systematic errors 3.3. Random measurement errors Part II. MEASUREMENT TECHNOLOGY 4. Introduction to measurement technology 5. Measurements of mechanical quantities 5.1. Linear measurements 5.2. Roughness measurements 5.3. Hardness measurements 5.4. Pressure measurements 5.5. Mass and force measurements 5.6. Viscosity measurements 5.7. Density measurement 6. Temperature measurements 6.1. Temperature measurement methods 6.2. Contact thermometers 6.3. Non-contact thermometers 7. Electrical and magnetic measurements 7.1. Measurements of electrical quantities 7.2. Principles behind magnetic measurements 7.3. Magnetic transducers 7.4. Instruments for measuring the parameters of magnetic fields 7.5. Quantum magnetometric and galvanomagnetic devices 7.6. Induction magnetometric instruments 8. Optical measurements 8.1. General provisions 8.2. Photometric instruments 8.3. Spectral measuring instruments 8.4. Filter Spectral Instruments 8.5. Interference Spectral Instruments 9. PHYSICAL AND CHEMICAL MEASUREMENTS 9.1. Features of measuring the composition of substances and materials 9.2. Moisture measurements of substances and materials 9.3. Analysis of the composition of gas mixtures 9.4. Measurements of the composition of liquids and solids 9.5. Metrological support of physical and chemical measurements Part III. STANDARDIZATION AND CERTIFICATION 10. Organizational and methodological foundations of metrology and standardization 10.1. Introduction 10.2. Legal basis of metrology and standardization 10.3. International organizations for standardization and metrology 10.4. The structure and functions of the bodies of the State Standard of the Russian Federation 10.5. State services for metrology and standardization of the Russian Federation 10.6. Functions of metrological services of enterprises and institutions that are legal entities 11. The main provisions of the State Standardization Service of the Russian Federation 11.1. Scientific base of standardization of the Russian Federation 11.2. Bodies and services of standardization systems of the Russian Federation 11.3. Characteristics of standards of different categories 11.4. Catalogs and product classifiers as an object of standardization. Service standardization 12. Certification of measuring technology 12.1. Main goals and objectives of certification 12.2. Terms and definitions specific to certification 12.3. 12.3. Systems and certification schemes 12.4. Mandatory and voluntary certification 12.5. Rules and procedures for certification 12.6. Accreditation of certification bodies 12.7. Service certification Conclusion Applications

Foreword

The content of the concepts of "metrology" and "standardization" is still the subject of discussion, although the need for a professional approach to these problems is obvious. So in recent years, numerous works have appeared in which metrology and standardization are presented as a tool for certification of measuring equipment, goods and services. By such a formulation of the question, all the concepts of metrology are belittled and make sense as a set of rules, laws, documents that make it possible to ensure the high quality of commercial products.

In fact, metrology and standardization have been a very serious scientific pursuit since the founding of the Depot of Exemplary Measures in Russia (1842), which was then transformed into the Main Chamber of Weights and Measures of Russia, headed for many years by the great scientist D.I. Mendeleev. Our country was one of the founders of the Metric Convention, adopted 125 years ago. During the years of Soviet power, a system of standardization of countries for mutual economic assistance was created. All this indicates that in our country metrology and standardization have long been fundamental in the organization of the system of weights and measures. It is these moments that are eternal and should have state support. With the development of market relations, the reputation of manufacturers should become a guarantee of the quality of goods, and metrology and standardization should play the role of state scientific and methodological centers, which contain the most accurate measuring instruments, the most promising technologies, and employ the most qualified specialists.

In this book, metrology is considered as a field of science, primarily physics, which should ensure the uniformity of measurements at the state level. Simply put, there must be a system in science that allows representatives of various sciences, such as physics, chemistry, biology, medicine, geology, etc., to speak the same language and understand each other. The means of achieving this result are the constituent parts of metrology: systems of units, standards, standard samples, reference data, terminology, theory of errors, system of standards. The first part of the book is devoted to the basics of metrology.

The second part is devoted to describing the principles of creating measuring equipment. The sections of this part are presented in the same way as the types of measurements are organized in the system of the State Standard of the Russian Federation: mechanical, temperature, electrical and magnetic, optical and physico-chemical. Measuring technology is considered as an area of ​​direct use of the achievements of metrology.

The third part of the book is a brief description of the essence of certification - the field of activity of modern centers of metrology and standardization in our country. Since the standards vary from country to country, there is a need to check all aspects of international cooperation (goods, measuring equipment, services) for compliance with the standards of the countries where they are used.

The book is intended for a wide range of specialists working with specific measuring instruments in various fields of activity from trade to quality control of technological processes and measurements in ecology. The presentation omits the details of some sections of physics that do not have a defining metrological character and are available in the specialized literature. Much attention is paid to the physical meaning of using the metrological approach to solving practical problems. It is assumed that the reader is familiar with the basics of physics and has at least a general understanding of modern achievements in science and technology, such as laser technology, superconductivity, etc.

The book is intended for professionals who use certain instruments and are interested in providing the measurements they need in an optimal way. These are undergraduate and graduate students of universities who specialize in the sciences based on measurements. We would like to see the presented material as a link between the courses of general scientific disciplines and special courses on presenting the essence of modern production technologies.

The material was written on the basis of a course of lectures on metrology and standardization delivered by the author at the St. Petersburg Institute of the Moscow State University of Printing Arts and at St. Petersburg State University. This made it possible to correct the presentation of the material, making it understandable for students of various specialties, from applicants to senior students.

The author expects the material to be in line with the fundamental concepts of metrology and standardization based on the experience of personal work for almost a decade and a half in the State Standard of the USSR and the State Standard of the Russian Federation.

Test

Discipline: "Electrical measurements"

Introduction1. Measurement of electrical circuit and insulation resistance2. Measurement of active and reactive power3. Measurement of magnetic quantitiesReferences
Introduction Problems of magnetic measurements. The field of electrical measuring technology that deals with the measurement of magnetic quantities is usually called magnetic measurements. A wide variety of problems are currently being solved with the help of methods and equipment for magnetic measurements. The main ones are the following: measurement of magnetic quantities (magnetic induction, magnetic flux, magnetic moment, etc.); characterization of magnetic materials; study of electromagnetic mechanisms; measurement of the magnetic field of the Earth and other planets; study of the physicochemical properties of materials (magnetic analysis); study of the magnetic properties of the atom and atomic nucleus; determination of defects in materials and products (magnetic flaw detection), etc. Despite the variety of tasks , solved with the help of magnetic measurements, usually only a few basic magnetic quantities are determined: The magnetic quantity of interest to us is determined by calculation on the basis of known relationships between magnetic and electrical quantities. The theoretical basis of such methods is Maxwell's second equation, which relates the magnetic field to the electric field; these fields are two manifestations of a special kind of matter called the electromagnetic field. Other (not only electrical) manifestations of the magnetic field, such as mechanical, optical, are also used in magnetic measurements. This chapter introduces the reader only to some methods for determining its basic magnetic quantities and characteristics of magnetic materials .

1. Measuring the resistance of the electrical circuit and insulation

Measuring instruments

Insulation measuring instruments include megohmmeters: ESO 202, F4100, M4100/1-M4100/5, M4107/1, M4107/2, F4101. F4102/1, F4102/2, BM200/G and others produced by domestic and foreign companies. Insulation resistance is measured with megohmmeters (100-2500V) with measured values ​​in Ohm, kOhm and MOhm.

1. To perform insulation resistance measurements, trained electrical personnel are allowed who have a knowledge test certificate and an electrical safety qualification group of at least 3rd, when performing measurements in installations up to 1000 V, and not lower than 4th, when measuring in installations above 1000 AT.

2. Persons from electrical personnel with secondary or higher specialized education may be allowed to process measurement results.

3. Analysis of the measurement results should be carried out by personnel dealing with the insulation of electrical equipment, cables and wires.

Safety requirements

1. When performing measurements of insulation resistance, safety requirements must be observed in accordance with GOST 12.3.019.80, GOST 12.2.007-75, Rules for the operation of consumer electrical installations and Safety regulations for the operation of consumer electrical installations.

2. The premises used for measuring insulation must meet the requirements of explosion and fire safety in accordance with GOST 12.01.004-91.

3. Measuring instruments must meet the safety requirements in accordance with GOST 2226182.

4. Measurements with a megohmmeter are allowed to be carried out by trained persons from electrical personnel. In installations with voltages above 1000 V, measurements are taken along by two persons, one of whom must have at least group IV in electrical safety. Measurements during installation or repair are specified in the work order in the line "Assigned". In installations with voltages up to 1000 V, measurements are performed by order of two persons, one of whom must have a group of at least III. The exception is the tests specified in paragraph BS.7.20.

5. Measurement of the insulation of a line that can receive voltage from two sides is only allowed if a message is received from the responsible person of the electrical installation, which is connected to the other end of this line, by telephone, by courier, etc. (with a reverse check) that the line disconnectors and the switch are turned off and the poster "Do not turn on. People are working" is posted.

6. Before starting the tests, it is necessary to make sure that there are no people working on that part of the electrical installation to which the test device is connected, to prohibit persons located near it from touching live parts and, if necessary, set the guard.

7. To control the state of insulation of electrical machines in accordance with the guidelines or programs, measurements with a megohmmeter on a stopped or rotating, but not excited machine, can be carried out by operational personnel or, by his order, in the order of current operation by employees of an electrical laboratory. Under the supervision of operating personnel, these measurements can also be performed by maintenance personnel. Tests of insulation of rotors, armatures and excitation circuits can be carried out by one person with an electrical safety group of at least III, tests of stator insulation by at least two persons, one of whom must have a group of at least IV, and the second - at least III.

8. When working with a megohmmeter, it is forbidden to touch the live parts to which it is attached. After completion of work, it is necessary to remove the residual charge from the equipment under test by means of its short-term grounding. The person discharging the residual charge must wear dielectric gloves and stand on an insulated base.

9. Measurements with a megohmmeter are prohibited: on one circuit of double-circuit lines with a voltage above 1000 V, while the other circuit is energized; on a single-circuit line, if it runs in parallel with a working line with a voltage above 1000 V; during or near a thunderstorm.

10. Measurement of insulation resistance with a megohmmeter is carried out on disconnected current-carrying parts, from which the charge is removed by preliminary grounding. Grounding from current-carrying parts should be removed only after connecting the megohmmeter. When removing grounding, dielectric gloves must be used.

Measurement conditions

1. Insulation measurements should be carried out in normal climatic conditions in accordance with GOST 15150-85 and in the normal mode of the supply network or specified in the factory passport - technical description for megohmmeters.

2. The value of the electrical resistance of the insulation of the connecting wires of the measuring circuit must exceed at least 20 times the minimum allowable value of the electrical resistance of the insulation of the tested product.

3. The measurement is carried out indoors at a temperature of 25 ± 10 ° C and a relative air humidity of not more than 80%, unless other conditions are provided for in the standards or technical specifications for cables, wires, cords and equipment.

Preparing to take measurements

In preparation for performing insulation resistance measurements, the following operations are carried out:

1. They check the climatic conditions at the place where the insulation resistance is measured with the measurement of temperature and humidity and the compliance of the room with regard to explosion and fire hazard for the selection of a megohmmeter to the appropriate conditions.

2. By external inspection, check the condition of the selected megohmmeter, connecting conductors, the operability of the megohmmeter according to the technical description for the megohmmeter.

3. Check the period of validity of the state verification on the megohmmeter.

4. Preparation of measurements of samples of cables and wires is performed in accordance with GOST 3345-76.

5. When performing periodic preventive maintenance in electrical installations, as well as when performing work at reconstructed facilities in electrical installations, the preparation of the workplace is carried out by the electrical personnel of the enterprise, where work is performed in accordance with the rules of PTBEEP and PEEP.

Taking measurements

1. The reading of the values ​​of the electrical resistance of the insulation during the measurement is carried out after 1 min from the moment the measuring voltage is applied to the sample, but not more than 5 min, unless other requirements are provided in the standards or specifications for specific cable products or other measured equipment.

Before re-measurement, all metal elements of the cable product must be grounded for at least 2 minutes.

2. The electrical resistance of the insulation of individual cores of single-core cables, wires and cords must be measured:

for products without a metal sheath, screen and armor - between a conductive core and a metal rod or between a core and grounding;

for products with a metal sheath, screen and armor - between a conductive core and a metal sheath or screen, or armor.

3. The electrical resistance of the insulation of multi-core cables, wires and cords must be measured:

for products without a metal sheath, screen and armor - between each conductive core and the rest of the cores connected to each other or between each conductive one; residential and other conductors interconnected and grounded;

for products with a metal sheath, screen and armor - between each conductive core and the rest of the cores connected to each other and to the metal sheath or screen or armor.

4. With a reduced insulation resistance of cables, wires and cords, which is different from the regulatory rules of PUE, PEEP, GOST, it is necessary to perform repeated measurements with disconnecting cables, wires and cords from consumer clamps and diluting current-carrying cores.

5. When measuring the insulation resistance of individual samples of cables, wires and cords, they must be selected for building lengths wound on drums or in coils, or samples with a length of at least 10 m, excluding the length of the end grooves, if in the standards or specifications for cables , wires and cords other lengths are not specified. The number of building lengths and samples for measurement must be indicated in the standards or specifications for cables, wires and cords.

One of the important concepts in the theory and practice of measurements is the concept of a physical quantity. Physical quantity- a property that is qualitatively common to many objects, but quantitatively individual for each of them.

Measurement physical quantity is finding its value experimentally with the help of special technical means. According to the method of obtaining the numerical value of the measured value, all measurements are divided into direct, indirect, cumulative and joint.

Direct measurements are based on the method of comparing the measured quantity with the measure of this quantity or on the method of directly assessing the value of the measured quantity using a reading device, the scale of which is graduated in units of the measured quantity. An example of direct measurements is the measurement of current with an ammeter.

Indirect measurements- measurements, the result of which is obtained after direct measurements of quantities related to the measured quantity by a known relationship. So, the measurement of electrical resistance in a DC circuit is carried out by direct measurements of the current strength with an ammeter and voltage with a voltmeter, followed by the calculation of the desired resistance value.

Cumulative measurements are repeated, usually direct measurements of one or more quantities of the same name with the receipt of a general measurement result by solving a system of equations compiled from particular measurement results. As an example, here is the process of determining the mutual inductance between two coils by measuring their total inductance twice. First, the coils are connected so that their magnetic fields add up, and the total inductance is measured: L 01 \u003d L 1 + L 2 + 2M, where M is the mutual inductance; L 1 , L 2 - inductances of the first and second coils. Then the coils are connected so that their magnetic fields are subtracted, and the total inductance is measured: L 02 \u003d L 1 + L 2 - 2M. The desired value of M is determined by solving these equations: M = (L 01 - L 02)/4.

Joint measurements consist in the simultaneous measurement of two or more dissimilar quantities with the subsequent calculation of the result by solving a system of equations obtained during the measurements. Let, for example, it is required to find the temperature coefficients A, B of the thermistor R t \u003d R 0 (1 + AT + BT 2), where R 0 is the resistance value at T 0 \u003d 20 ° C, T is the temperature of the medium. By measuring the resistance values ​​R 0 , R 1 , R 2 of the thermistor at temperatures T 0 , T 1 , T 2 determined using a thermometer, and solving the resulting system of three equations, we find the values ​​of A and B.

measuring instrument- a technical device used in measurements and having normalized metrological characteristics. Measuring instruments include measures, measuring transducers, measuring devices and measuring systems.

Measure- a measuring instrument designed to store and reproduce a physical quantity of a given size. The measures include normal elements, resistance boxes, standard signal generators, graduated scales of indicating instruments.

Measuring transducers- measuring instruments designed to convert the measuring signal into a form convenient for transmission, storage and processing.

Measuring instruments- measuring instruments designed to generate a signal of measuring information, functionally related to the numerical value of the measured quantity, and display this signal on the reading device or its registration.

Measuring system- a set of measuring instruments and auxiliary devices that provide measurement information on the object under study in a given volume and given conditions.

The most important properties of measuring instruments are metrological properties. Metrological properties (characteristics) include accuracy, measurement range, sensitivity, speed, etc.

Minsk: BNTU, 2003. - 116 p. Introduction.
Classification of physical quantities.
The size of physical quantities. The true value of physical quantities.
The main postulate and axiom of the theory of measurements.
Theoretical models of material objects, phenomena and processes.
physical models.
mathematical models.
Errors of theoretical models.
General characteristics of the concept of measurement (information from metrology).
Classification of measurements.
Measurement as a physical process.
Methods of measurement as methods of comparison with a measure.
Methods of direct comparison.
Method of direct assessment.
Direct conversion method.
replacement method.
Scale transformation methods.
shunt method.
Follow-up balancing method.
Bridge method.
difference method.
Zero methods.
Sweep compensation method.
Measuring transformations of physical quantities.
Classification of measuring transducers.
Static characteristics and static errors of SI.
Characteristics of the impact (influence) of the environment and objects on the SI.
SI sensitivity bands and uncertainty intervals.
MI with additive error (zero error).
SI with multiplicative error.
SI with additive and multiplicative errors.
Measurement of large quantities.
Formulas for static errors of measuring instruments.
Full and working ranges of measuring instruments.
Dynamic errors of measuring instruments.
Dynamic error of the integrating link.
Causes of additive errors in SI.
Influence of dry friction on moving elements of SI.
SI construction.
Contact potential difference and thermoelectricity.
Contact potential difference.
thermoelectric current.
Interference due to poor grounding.
Causes of multiplicative SI errors.
Aging and instability of SI parameters.
Nonlinearity of the transformation function.
Geometric non-linearity.
Physical non-linearity.
leakage currents.
Measures of active and passive protection.
Physics of random processes that determine the minimum measurement error.
Possibilities of the human eye.
Natural limits of measurements.
Heisenberg uncertainty relations.
Natural spectral width of emission lines.
The absolute limit of the accuracy of measuring the intensity and phase of electromagnetic signals.
Photon noise of coherent radiation.
Equivalent noise temperature of radiation.
Electrical interference, fluctuations and noise.
Physics of internal non-equilibrium electrical noise.
Shot noise.
Noise generation - recombination.
1/f noise and its versatility.
impulse noise.
Physics of internal equilibrium noises.
Statistical model of thermal fluctuations in equilibrium systems.
Mathematical model of fluctuations.
The simplest physical model of equilibrium fluctuations.
Basic formula for calculating fluctuation dispersion.
Influence of fluctuations on the sensitivity threshold of instruments.
Examples of calculation of thermal fluctuations of mechanical quantities.
The speed of a free body.
Oscillations of a mathematical pendulum.
Rotations of an elastically suspended mirror.
Displacement of spring weights.
Thermal fluctuations in an electrical oscillatory circuit.
Correlation function and noise power spectral density.
Fluctuation-dissipation theorem.
Nyquist formulas.
Spectral density of voltage and current fluctuations in an oscillatory circuit.
Equivalent temperature of non-thermal noise.
External electromagnetic noise and interference and methods for their reduction.
Capacitive coupling (capacitive noise pickup).
Inductive coupling (inductive noise pickup).
Shielding conductors from magnetic fields.
Features of a conductive screen without current.
Features of a conductive screen with current.
Magnetic connection between a screen with current and a conductor enclosed in it.
Using a conductive shield with current as a signal conductor.
Protection of space from the radiation of a conductor with current.
Analysis of various signal circuit protection schemes by shielding.
Comparison of coaxial cable and shielded twisted pair.
Screen features in the form of a braid.
Influence of current inhomogeneity in the screen.
selective screening.
Suppression of noise in the signal circuit by its balancing method.
Additional noise reduction methods.
Nutrition link.
Decoupling filters.
Protection against radiation of high-frequency noisy elements and circuits.
Noise in digital circuits.
Conclusions.
The use of thin sheet metal screens.
near and far electromagnetic fields.
shielding efficiency.
Total characteristic impedance and screen resistance.
absorption loss.
Reflection loss.
Total absorption and reflection losses for the magnetic field.
Influence of holes on shielding efficiency.
Influence of cracks and holes.
Using a waveguide at a frequency below the cutoff frequency.
Influence of round holes.
Use of conductive spacers to reduce radiation in gaps.
Conclusions.
Noise characteristics of contacts and their protection.
Smoldering discharge.
Arc discharge.
Comparison of AC and DC circuits.
Contact material.
inductive loads.
Contact protection principles.
Transient suppression for inductive loads.
Contact protection circuits for inductive loads.
Chain with capacity.
Circuit with capacitance and resistor.
Circuit with capacitance, resistor and diode.
Contact protection with resistive load.
Recommendations for the selection of contact protection circuits.
Passport data for contacts.
Conclusions.
General methods for improving the accuracy of measurements.
Method of matching measuring transducers.
Ideal current generator and ideal voltage generator.
Matching the resistance of generator IP.
Matching the resistance of parametric transducers.
The fundamental difference between information and energy chains.
Use of matching transformers.
Negative feedback method.
Bandwidth reduction method.
Equivalent noise bandwidth.
Signal averaging (accumulation) method.
Signal and noise filtering method.
Problems of creating an optimal filter.
Useful signal spectrum transfer method.
Phase detection method.
Synchronous detection method.
Noise integration error using RC chain.
SI conversion factor modulation method.
The use of signal modulation to increase its noise immunity.
The method of differential inclusion of two IP.
Method for correction of MI elements.
Methods for reducing the influence of the environment and changing conditions.
Organization of measurements.

MINISTRY OF EDUCATION OF THE RUSSIAN FEDERATION EAST SIBERIAN STATE TECHNOLOGICAL UNIVERSITY

Department "Metrology, standardization and certification

PHYSICAL BASIS OF MEASUREMENTS

Course of lectures "Universal physical constants"

Compiled by: Zhargalov B.S.

Ulan-Ude, 2002

The course of lectures "Universal physical constants" is intended for students of the direction "Metrology, standardization and certification" when studying the discipline "Physical foundations of measurements". The paper gives a brief overview of the history of discoveries of physical constants by the world's leading physicists, which subsequently formed the basis of the international system of units of physical quantities.

Introduction Gravitational constant

Avogadro and Boltzmann's constant Faraday's constant Charge and mass of an electron Speed ​​of light

Rydberg Planck constants Proton and neutron rest mass Conclusion References

Introduction

Universal physical constants are quantities that are included as quantitative coefficients in mathematical expressions of fundamental physical laws or are characteristics of micro-objects.

The table of universal physical constants should not be taken as something already completed. The development of physics continues, and this process will inevitably be accompanied by the appearance of new constants, which today we have no idea about.

Table 1

Universal physical constants

Name				Numeric value
Gravity				6.6720*10-11 N*m2 *kg-2
constant
Avogadro constant				6.022045*1022 mol-1
Boltzmann constant				1.380662*10-23 J*K-1
Faraday constant				9.648456*104 C*mol-1
Electron charge				1.6021892*10-19 C
Rest mass of an electron				9.109534*10-31kg
Speed				2.99792458*108 m*s-2
Planck's constant				6.626176*10-34*J*s
Rydberg constant			R∞	1.0973731*10-7*m--1
Rest mass of a proton				1.6726485*10-27kg
Neutron rest mass				1.6749543*10-27kg

Looking at the table, you can see that the values ​​of the constants are measured with great accuracy. However, perhaps a more accurate knowledge of the value of one or another constant turns out to be fundamentally important for science, since this is often a criterion for the validity of one physical theory or the fallacy of another. Reliably measured experimental data are the foundation for building new theories.

The accuracy of measuring physical constants is the accuracy of our knowledge about the properties of the surrounding world. It makes it possible to compare the conclusions of the basic laws of physics and chemistry.

Gravitational constant

The causes of the attraction of bodies to each other have been discussed since ancient times. One of the thinkers of the ancient world - Aristotle (384-322 BC) divided all bodies into heavy and light. Heavy bodies - stones fall down, trying to reach a certain "center of the world" introduced by Aristotle, light bodies - smoke from a fire - fly up. According to the teachings of another ancient Greek philosopher, Ptolemy, the “center of the world” was the Earth, while all other celestial bodies revolved around it. The authority of Aristotle was so great that until the fifteenth century. his views were not questioned.

Leonardo da Vinci (14521519) was the first to criticize the assumption of the "Center of the World". The failure of Aristotle's views was shown by the experience of the first in the history of physics

scientist-experimenter G. Galileo (1564-1642). He dropped a cast-iron cannonball and a wooden ball from the top of the famous Leaning Tower of Pisa. Objects of different mass fell to Earth at the same time. The simplicity of Galileo's experiments does not detract from their significance, since these were the first experimental facts reliably established by measurements.

All bodies fall to the Earth with the same acceleration - this is the main conclusion from Galileo's experiments. He also measured the value of the free fall acceleration, which, taking into account

solar system revolve around the sun. However, Copernicus was unable to indicate the reasons under which this rotation occurs. The laws of planetary motion were deduced in their final form by the German astronomer J. Kepler (1571-1630). Kepler still did not understand that the force of gravity determines the motion of the planets. Englishman R. Cook in 1674

He showed that the movement of the planets in elliptical orbits is consistent with the assumption that they are all attracted by the Sun.

Isaac Newton (1642-1727) at the age of 23 came to the conclusion that the movement of the planets occurs under the action of a radial force of attraction directed towards the sun and modulo inversely proportional to the square of the distance between the Sun and the planet.

But this assumption had to be verified by Newton, assuming that the gravitational force of the same origin keeps its satellite, the Moon, near the Earth, performed a simple calculation. He proceeded from the following: the Moon moves around the Sun in an orbit that can be considered circular in the first approximation. Its centripetal acceleration a can be calculated by the formula

a \u003d rω 2

where r is the distance from the Earth to the Moon, and ω is the angular acceleration of the Moon. The value of r is equal to sixty earth radii (R3 = 6370 km). The acceleration ω is calculated from the period of revolution of the Moon around the Earth, which is equal to 27.3 days: ω = 2π rad/27.3 days

Then the acceleration is equal to:

a \u003d r ω 2 \u003d 60 * 6370 * 105 * (2 * 3.14 / 27.3 * 86400) 2 cm / s2 \u003d 0.27 cm / s2

But if it is true that the forces of gravity decrease inversely with the square of the distance, then the acceleration of free fall g l on the moon should be:

g l \u003d go / (60) 2 \u003d 980 / 3600 cm / s2 \u003d 0.27 cm / s3

As a result of calculations, the equality

a \u003d g l,

those. the force that keeps the moon in orbit is nothing more than the force of attraction of the moon by the earth. The same equality shows the validity of Newton's assumptions about the nature of the change in force with distance. All this gave Newton reason to write down the law of gravitation in

final mathematical form:

F=G (M1 M2 /r2 )

where F is the force of mutual attraction acting between two masses M1 and M2 separated from each other by a distance r.

The coefficient G, which is part of the law of universal gravitation, is still a mysterious gravitational constant. Nothing is known about it - neither its meaning, nor its dependence on the properties of attracting bodies.

Since this law was formulated by Newton simultaneously with the laws of motion of bodies (the laws of dynamics), scientists were able to theoretically calculate the orbits of the planets.

In 1682, the English astronomer E. Halley, using Newton's formulas, calculated the time of the second arrival to the Sun of a bright comet observed at that time in the sky. The comet returned strictly at the estimated time, confirming the truth of the theory.

The significance of Newton's law of gravitation was fully manifested in the history of the discovery of a new planet.

In 1846, the French astronomer W. Le Verrier calculated the position of this new planet. After he reported its celestial coordinates to the German astronomer I. Halle, an unknown planet, later named Neptune, was discovered exactly in the calculated place.

Despite the obvious successes, Newton's theory of gravitation was not finally recognized for a long time. The value of the gravitational constant G in the formula of the law was known.

Without knowing the value of the gravitational constant G, it is impossible to calculate F. However, we know the free fall acceleration of bodies: go = 9.8 m/s2, which allows us to theoretically estimate the value of the gravitational constant G. Indeed, the force under which the ball falls to the Earth is the force attraction of the ball by the Earth:

F1 =G(M111 M 3 /R3 2 )

According to the second law of dynamics, this force will give the body the acceleration of free fall:

g 0=F/M 111=G M 3/R 32

Knowing the value of the mass of the Earth and its radius, it is possible to calculate the value of the gravitational

constant:

G=g0 R3 2 / M 3= 9.8*(6370*103)2 /6*1024 m3/s2 kg=6.6*10-11 m3/s2 kg

In 1798, the English physicist G. Cavendish discovered the attraction between small bodies in terrestrial conditions. Two small lead balls weighing 730 g were suspended from the ends of the rocker. Then two large lead balls weighing 158 kg were brought to these balls. In these experiments, Cavendish first observed the attraction of bodies to each other. He also experimentally determined the value of the gravitational

constant:

G \u003d (6.6 + 0.041) * 10-11 m3 / (s2 kg)

Cavendish's experiments are of great importance for physics. Firstly, the value of the gravitational constant was measured, and secondly, these experiments proved the universality of the law of gravity.

Avogadro and Boltzmann constants

How the world works has been speculated since ancient times. Supporters of one point of view believed that there is a certain primary element from which all substances consist. Such an element, according to the ancient Greek philosopher Geosidas, was the Earth, Thales assumed water as the primary element, Anaximenes air, Heraclitus - fire, Empedocles allowed the simultaneous existence of all four primary elements. Plato believed that under certain conditions, one primary element can pass into another.

There was also a fundamentally different point of view. Leucippus, Democritus and Epicurus represented matter as consisting of small, indivisible and impenetrable particles, differing from each other in size and shape. They called these particles atoms (from the Greek "atomos" - indivisible). A look at the structure of matter was not supported experimentally, but can be considered an intuitive guess of ancient scientists.

For the first time, the corpuscular theory of the structure of matter, in which the structure of matter was explained from an atomistic position, was created by the English scientist R. Boyle (1627-1691).

The French scientist A. Lavoisier (1743-1794) gave the first classification of chemical elements in the history of science.

The corpuscular theory was further developed in the works of the outstanding English chemist J. Dalton (1776-1844). In 1803 Dalton discovered the law of simple multiple ratios, according to which various elements can combine with each other in ratios of 1:1, 1:2, etc.

The paradox of the history of science is Dalton's absolute non-recognition of the law of simple volumetric relations discovered in 1808 by the French scientist J. Gay-Lusac. According to this law, the volumes of both the gases involved in the reaction and the gaseous reaction products are in simple multiple ratios. For example, combining 2 liters of hydrogen and 1 liter of oxygen gives 2 liters. water vapor. This contradicted Dalton's theory and rejected Gay-lusak's law as inconsistent with his atomic theory.

The way out of this crisis was indicated by Amedeo Avogadro. He found a way to combine Dalton's atomistic theory with Gay-Lusac's law. The hypothesis is that the number of molecules is always the same in equal volumes of any gases, or is always proportional to the volumes. Avogadro thus for the first time introduces into science the concept of a molecule as a combination of atoms. This explained the results of Gay-Lusac: 2 liters of hydrogen molecules in combination with 1 liter of oxygen molecules give 2 liters of water vapor molecules:

2H2 + O2 \u003d 2H2 O

Avogadro's hypothesis acquires exceptional importance due to the fact that it implies the existence of a constant number of molecules in a mole of any substance. Indeed, if we denote the molar mass (the mass of a substance taken in the amount of one mole) through M, and the relative molecular mass through m, then it is obvious that

M=NA m

where NA is the number of molecules in a mole. It is the same for all substances:

NA =M/m

Using this, one can obtain another important result. Avogadro's hypothesis states that the same number of gas molecules always occupy the same volume. Therefore, the volume Vo occupied by a mole of any gas under normal conditions (temperature 0Co and pressure 1.013*105 Pa) is a constant value. This molar

the volume was soon changed experimentally and turned out to be equal to: Vo = 22.41 * 10-3 m3

One of the primary tasks of physics was to determine the number of molecules in a mole of any substance NA, which later received the Avogadro constant.

The Austrian scientist Ludwig Boltzmann (1844-1906), an outstanding theoretical physicist, author of numerous fundamental studies in various fields of physics, he ardently defended the anatomical hypothesis.

Boltzmann was the first to consider the important question of the distribution of thermal energy over different degrees of freedom of gas particles. He strictly showed that the average kinematic energy of gas particles E is proportional to the absolute temperature T:

E T The coefficient of proportionality can be found using the basic equation

molecular kinematic theory:

p \u003d 2/3 pU

Where p is the concentration of gas molecules. Multiplying both sides of this equation by the molecular volume Vo. Since n Vo is the number of molecules in a mole of gas, we get:

p Vo == 2/3 NA E

On the other hand, the ideal gas equation of state defines the product p

Vo as

p Vo =RT

Therefore, 2/3 NA E = RT

Or E=3RT/2NA

The R/NA ratio is a constant value, the same for all for all substances. This new universal physical constant received, at the suggestion of M.

plank, name Boltzmann constant k

k=R/NA.

Boltzmann's merits in the creation of the molecular-kinetic theory of gases were thus duly recognized.

The numerical value of the Boltzmann constant is: k= R/NA =8.31 ​​J mol/6.023*1023 K mol=1.38*10-16 J/K.

Boltzmann's constant, as it were, connects the characteristics of the microworld (average kinetic energy of particles E) and the characteristics of the macrocosm (gas pressure and temperature).

Faraday constant

The study of phenomena, one way or another related to the electron and its movement, made it possible to explain from a unified position the most diverse physical phenomena: electricity and magnetism, light and electromagnetic oscillations. The structure of the atom and the physics of elementary particles.

As far back as 600 BC. Thales of Miletus discovered the attraction of light bodies (fluffs, pieces of paper) with rubbed amber (amber means electron in ancient Greek).

Works that qualitatively describe certain electrical phenomena. appeared at first very sparingly. In 1729, S. Gray established the division of bodies into conductors of electric current and insulators. The Frenchman C. Dufay discovered that sealing wax rubbed with fur is also electrified, but opposite to the electrification of a glass rod.

The first work in which an attempt was made to theoretically explain electrical phenomena was written by the American physicist W. Franklin in 1747. To explain electrification, he proposed the existence of a certain “electric fluid” (fluid), which is included as an integral part in any matter. He associated the existence of two types of electricity with the existence of two types of liquids - "positive" and "negative". Having discovered. that when glass and silk are rubbed against each other, they electrify differently.

It was Franklin who first suggested the atomic, granular nature of electricity "Electrical matter consists of particles that must be extremely small."

The basic concepts in the science of electricity were formulated only after the first quantitative studies appeared. Measuring the force of interaction of electric charges, the French scientist C. Coulomb in 1785 established the law

interactions of electric charges:

F= k q1 q2 /r2

where q1 and q 2 are electric charges, r is the distance between them,

F is the force of interaction between charges, k is the coefficient of proportionality. Difficulties in using electrical phenomena were largely due to the fact that scientists did not have a convenient source of electric current at their disposal. Such

the source was invented by the Italian scientist A. Volta in 1800 - it was a column of zinc and silver circles separated by paper soaked in salted water. Intensive studies began on the passage of current through various substances.

electrolysis, it contained the first indications of that. that matter and electricity are related to each other. The most important quantitative research in the field of electrolysis was carried out by the greatest English physicist M. Faraday (1791-1867). He found that the mass of the substance released on the electrode during the passage of an electric current is proportional to the strength of the current and time (Faraday's law of electrolysis). Based on this, he showed that in order to release the mass of a substance on the electrodes, numerically equal to M / n (M-molar the mass of the substance, n is its valency), a strictly defined charge F must be passed through the electrolyte. Thus, another important universal F appeared in physics, equal, as measurements showed, F = 96 484.5 C / mol.

Subsequently, the constant F was called the Faraday number. Analysis of the phenomenon of electrolysis led Faraday to the idea that the carrier of electrical forces are not any electrical liquids, but atoms-particles of matter. “Atoms of matter are somehow endowed with electrical forces,” he says.

Faraday first discovered the influence of the medium on the interaction of electric charges and specified the form of Coulomb's law:

F= q1 q2/ ε r2

Here, ε is a characteristic of the medium, the so-called dielectric constant. Based on these studies, Faraday rejected the action of electric charges at a distance (without an intermediate medium) and introduced into physics a completely new and important idea that the electric field is the carrier and transmitter of electrical influence!

Charge and mass of an electron

Experiments to determine the Avogadro constant made physicists think about whether too much importance is attached to the characteristics of the electric field. Is there not a more concrete, more material carrier of electricity? For the first time this idea is clearly in 1881. G. Helmolts expressed: “If we admit the existence of chemical atoms, then we are forced to conclude from here further that electricity, both positive and negative, is also divided into certain elemental quantities that play the role of electricity atoms.”

The calculation of this "certain elemental amount of electricity" was performed by the Irish physicist J. Stoney (1826-1911). It is extremely simple. If the release of one mole of a monovalent element during electrolysis requires a charge equal to 96484.5 C, and one mole contains 6 * 1023 atoms, then it is obvious that by dividing the Faraday number F by the Avogadro number NA, we get the amount of electricity required to release one

atom of matter. Let us denote this minimum portion of electricity by e:

E \u003d F / NA \u003d 1.6 * 10-18 C.

In 1891, Stoney suggested calling this minimal amount of electricity an electron. Soon it was accepted by everyone.

The universal physical constants F and NA, in conjunction with the intellectual efforts of scientists, brought to life another constant - the electron charge e.

The fact of the existence of an electron as an independent physical particle was established in studies in the study of phenomena associated with the passage of electric current through gases. And again we must pay tribute to the insight of Faraday, who first began these studies in 1838. It was these studies that led to the discovery of the so-called cathode rays and ultimately to the discovery of the electron.

In order to make sure that the cathode rays really represent a stream of negatively charged particles, it was necessary to determine the mass of these particles and their charge in direct experiments. These experiments in 1897. carried out by the English physicist J. J. Thomson. At the same time, he used the deflection of cathode rays in the electric field of a capacitor and in a magnetic field. Calculations show that the angle

deflection of rays θ in an electric field of strength δ is equal to:

θ \u003d eδ / t * l / v2,

where e is the charge of the particle, m is its mass, l is the length of the capacitor,

v is the speed of the particle (it is known).

When the rays are deflected in a magnetic field B, the deflection angle α is equal to:

α = eV/t * l/v

At θ ≈ α (which was achieved in Thomson's experiments), it was possible to determine v, and then calculate and the ratio e / m is a constant independent of the nature of the gas. Thomson

the first clearly formulated the idea of ​​the existence of a new elementary particle of matter, so he is rightfully considered the discoverer of the electron.

The honor of directly measuring the charge of an electron and proving that this charge is indeed the smallest indivisible portion of electricity belongs to the remarkable American physicist R. E. Milliken. Drops of oil from a spray gun were injected into the space between the plates of the condenser through the upper window. Theory and experiment have shown that when a drop falls slowly, air resistance leads to the fact that its speed becomes constant. If the field strength ε between the plates is zero, then the drop velocity v 1 is equal to:

v1 = fP

where P is the weight of the drop,

f is the coefficient of proportionality.

In the presence of an electric field, the droplet velocity v 2 is determined by the expression:

v2 = f (q ε - P),

where q is the charge of the drop. (It is assumed that the force of gravity and the electric force are directed opposite each other.) From these expressions it follows that

q= P/ε v1 * (v1 + v2 ).

To measure the charge of drops, Millikan used

ionize the air. Air ions are captured by the droplets, as a result of which the charge of the droplets changes. If we denote the charge of the drop after ion capture as q ! , and its speed through v 2 1, then the change in charge delta q \u003d q! - q

delta q== P/ε v1 *(v1 - v2 ).,

the value of P/ ε v 1 for this drop is constant. Thus, the change in the charge of the drop turns out to be reduced to measuring the path traveled by the oil drop and the time during which this path was traveled. But time and path could be easily and fairly accurately determined by experience.

Numerous Millikan measurements have shown that always, regardless of the size of the drop, the change in charge is an integer multiple of some smallest charge e:

delta q=ne, where n is an integer. Thus, in the experiments of Millikan, the existence of a minimum amount of electricity e was established. Experiments convincingly proved the atomistic structure of electricity.

Experiments and calculations made it possible to determine the value of the charge e E = 1.6 * 10-19 C.

The reality of the existence of a minimum portion of electricity was proved; Millikan himself for these reactions in 1923. was awarded the Nobel Prize.

Now, using the value of the specific electron charge e/m and e known from Thomson's experiments, we can also calculate the mass of the electron m e.

Its value turned out to be:

i.e. \u003d 9.11 * 10-28 g.

speed of light

For the first time, the method of direct measurement of the speed of light was proposed by the founder of experimental physics, Galileo. His idea was very simple. Two observers with lamps were located at a distance of several kilometers from each other. The first opened the shutter on the lantern, sending a light signal in the direction of the second. The second, noticing the light of the lantern, opened the shutter of his own and sent a signal towards the first observer. The first observer measured the time t between his discovery

his lantern and the time when he noticed the light of the second lantern. The speed of light c is obviously equal to:

where S is the distance between observers, t is the measured time.

However, the first experiments undertaken in Florence according to this method did not give unambiguous results. The time interval t turned out to be very small and difficult to measure. Nevertheless, it followed from the experiments that the speed of light is finite.

The honor of the first measurement of the speed of light belongs to the Danish astronomer O. Roemer. Conducting in 1676. observing the eclipse of the satellite of Jupiter, he noticed that when the Earth is at a point of its orbit distant from Jupiter, the satellite Io appears from the shadow of Jupiter 22 minutes later. Explaining this, Roemer wrote: "This is the time the light uses to pass the place from my first observation to the present position." By dividing the diameter of the earth's orbit D by the delay time, it was possible to obtain the value of light c. At the time of Roemer, D was not known exactly, so from his measurements it followed that c ≈ 215,000 km/s. Subsequently, both the value of D and the delay time were refined, so now, using the Roemer method, we would get c ≈ 300,000 km/s.

Nearly 200 years after Roemer, the speed of light was measured for the first time in terrestrial laboratories. He did this in 1849. Frenchman L.Fizo. His method, in principle, did not differ from Galileo's, only the second observer was replaced by a reflecting mirror, and instead of a shutter opened by hand, a rapidly rotating gear wheel was used.

Fizeau placed one mirror in Suresnes, in his father's house, the other in Montmarte in Paris. The distance between the mirrors was L=8.66 km. The wheel had 720 teeth, the light reached its maximum intensity at the speed of rotation of the wheel, equal to 25 rpm. The scientist determined the speed of light using Galileo's formula:

The time t is obviously t = 1/25*1/720 s=1/18000 s and s=312,000 km/s

All the above measurements were carried out in air. The calculation of the velocity in vacuum was carried out using the known value of the refractive index of air. However, when measuring at large distances, an error could occur due to the inhomogeneity of the air. To eliminate this error, Michelson in 1932. measured the speed of light using the rotating prism method, but when light propagated in a pipe from which air was pumped out, he received

s=299 774 ± 2 km/s

The development of science and technology has made it possible to make some improvements in the old methods and to develop fundamentally new ones. So in 1928. the rotating gear wheel is replaced by an inertia-free electric light interrupter, while

С=299 788± 20 km/s

With the development of radar, new possibilities arose for measuring the speed of light. Aslakson, using this method in 1948, obtained the value c = 299 792 + 1.4 km / s, and Essen, using the method of microwave interference, c = 299 792 + 3 km / s. In 1967 measurements of the speed of light are performed with a helium-neon laser as a light source

Planck and Rydberg constants

Unlike many other universal physical constants, Planck's constant has an exact date of birth of December 14, 1900. On this day, M. Planck made a report at the German Physical Society, where, to explain the emissivity of an absolutely black body, a new value h appeared for physicists Proceeding from

from experimental data, Planck calculated its value: h = 6.62 * 10-34 J s.