A million people. Units. Basic information How b is measured

This guide has been compiled from various sources. But its creation was prompted by a small book "Mass Radio Library" published in 1964, as a translation of the book by O. Kroneger in the GDR in 1961. Despite its antiquity, it is my reference book (along with several other reference books). I think time has no power over such books, because the foundations of physics, electrical and radio engineering (electronics) are unshakable and eternal.

Units of measurement of mechanical and thermal quantities.

The units of measurement for all other physical quantities can be defined and expressed in terms of the basic units of measurement. The units obtained in this way, in contrast to the basic ones, are called derivatives. In order to obtain a derived unit of measurement of any quantity, it is necessary to choose a formula that would express this value in terms of other quantities already known to us, and assume that each of the known quantities included in the formula is equal to one unit of measurement. A number of mechanical quantities are listed below, formulas for their determination are given, it is shown how the units of measurement of these quantities are determined. Unit of speed v- meters per second (m/s) . Meter per second - the speed v of such a uniform movement, in which the body travels a path s equal to 1 m in time t \u003d 1 sec: 1v=1m/1sec=1m/sec Unit of acceleration A - meter per second squared (m/s 2). Meter per second squared - acceleration of such uniformly variable motion, in which the speed for 1 sec changes by 1 m!sec. Unit of force F - newton (And). newton - the force that gives the mass m in 1 kg an acceleration a equal to 1 m / s 2: 1n=1 kg×1m/s 2 =1(kg×m)/s 2 Unit of work A and energy- joule (j). Joule - the work done by the constant force F, equal to 1 n on the path s in 1 m, traveled by the body under the action of this force in the direction coinciding with the direction of the force: 1j=1n×1m=1n*m. Power unit W -watt (W). Watt - power at which work A is performed in time t \u003d -l sec, equal to 1 j: 1W=1J/1sec=1J/sec. Unit of quantity of heat q - joule (j). This unit is determined from the equality: which expresses the equivalence of thermal and mechanical energy. Coefficient k taken equal to one: 1j=1×1j=1j Units of measurement of electromagnetic quantities Unit of electric current A - ampere (A). The strength of an unchanging current, which, passing through two parallel rectilinear conductors of infinite length and negligible circular cross section, located at a distance of 1 m from one another in a vacuum, would cause a force equal to 2 × 10 -7 Newtons between these conductors. unit of quantity of electricity (unit of electric charge) Q- pendant (To). Pendant - the charge transferred through the cross section of the conductor in 1 sec at a current strength of 1 a: 1k=1a×1sec=1a×sec Unit of electrical potential difference (electrical voltage u, electromotive force E) - volt (V). Volt - the potential difference of two points of the electric field, when moving between which a charge Q of 1 k, work of 1 j is performed: 1w=1j/1k=1j/k Unit of electrical power R - watt (Tue): 1w=1v×1a=1v×a This unit is the same as the unit of mechanical power. Capacity unit WITH - farad (f). Farad - the capacitance of the conductor., whose potential rises by 1 V, if a charge of 1 k is applied to this conductor: 1f=1k/1v=1k/v Unit of electrical resistance R - ohm (ohm). - the resistance of such a conductor through which a current of 1 A flows at a voltage at the ends of the conductor of 1 V: 1om=1v/1a=1v/a Unit of absolute permittivity ε- farad per meter (f / m). farad per meter - absolute permittivity of the dielectric, when filled with a flat capacitor with plates with an area S of 1 m 2 each and the distance between the plates d ~ 1 m acquires a capacity of 1 f. The formula expressing the capacitance of a flat capacitor: From here 1f \ m \u003d (1f × 1m) / 1m 2 Unit of magnetic flux Ф and flux linkage ψ - volt-second or weber (wb). Weber - a magnetic flux, when it decreases to zero in 1 sec, an em arises in a circuit linked to this flux. d.s. induction equal to 1 in. Faraday - Maxwell's law: E i =Δψ / Δt Where Ei- e. d.s. induction that occurs in a closed circuit; ΔW is the change in the magnetic flux coupled to the circuit over time Δ t : 1vb=1v*1sec=1v*sec Recall that for a single loop of the concept of flow Ф and flux linkage ψ match up. For a solenoid with the number of turns ω, through the cross section of which the flow Ф flows, in the absence of scattering, the flux linkage Unit of magnetic induction B - tesla (tl). Tesla - induction of such a homogeneous magnetic field, in which the magnetic flux f through the area S of 1 m *, perpendicular to the direction of the field, is equal to 1 wb: 1tl \u003d 1vb / 1m 2 \u003d 1vb / m 2 Unit of magnetic field strength N - ampere per meter (a!m). Amp per meter - the strength of the magnetic field created by a rectilinear infinitely long current with a force of 4 pa at a distance r \u003d .2 m from the current-carrying conductor: 1a/m=4π a/2π * 2m Unit of inductance L and mutual inductance M - Henry (gn). - the inductance of such a circuit, with which a magnetic flux of 1 wb is cordoned off, when a current of 1 a flows through the circuit: 1gn \u003d (1v × 1sec) / 1a \u003d 1 (v × sec) / a Unit of magnetic permeability μ (mu) - henry per meter (gn/m). Henry per meter -absolute magnetic permeability of a substance in which, with a magnetic field strength of 1 a/m magnetic induction is 1 tl: 1g / m \u003d 1wb / m 2 / 1a / m \u003d 1wb / (a ​​× m)

Relations between units of magnetic quantities
in CGSM and SI systems

In electrical and reference literature published before the introduction of the SI system, the magnitude of the magnetic field strength H often expressed in oersteds (uh) magnetic induction value IN - in gauss (gs), magnetic flux Ф and flux linkage ψ - in maxwells (µs).

1e \u003d 1/4 π × 10 3 a / m; 1a / m \u003d 4π × 10 -3 e; 1gf=10 -4 t; 1tl=104 gs; 1mks=10 -8 wb; 1vb=10 8 ms

It should be noted that the equalities are written for the case of a rationalized practical MKSA system, which was included in the SI system as component. From a theoretical point of view, it would be better to O in all six relationships, replace the equal sign (=) with the match sign (^). For example

1e \u003d 1 / 4π × 10 3 a / m

which means: a field strength of 1 Oe corresponds to a strength of 1/4π × 10 3 a/m = 79.6 a/m

The point is that the units gs And ms belong to the CGMS system. In this system, the unit of current strength is not the main one, as in the SI system, but a derivative. Therefore, the dimensions of the quantities characterizing the same concept in the CGSM and SI systems turn out to be different, which can lead to misunderstandings and paradoxes, if we forget about this circumstance. When performing engineering calculations, when there is no basis for misunderstandings of this kind

Off-system units

Some mathematical and physical concepts
applied to radio engineering

Like the concept - the speed of movement, in mechanics, in radio engineering there are similar concepts, such as the rate of change of current and voltage. They can be either averaged over the course of the process, or instantaneous.

i \u003d (I 1 -I 0) / (t 2 -t 1) \u003d ΔI / Δt

With Δt -> 0, we get the instantaneous values ​​of the current change rate. It most accurately characterizes the nature of the change in the quantity and can be written as:

i=lim ΔI/Δt =dI/dt Δt->0

And you should pay attention - the average values ​​​​and instantaneous values ​​\u200b\u200bcan differ by dozens of times. This is especially evident when a changing current flows through circuits with a sufficiently large inductance.

decibell

To assess the ratio of two quantities of the same dimension in radio engineering, a special unit is used - the decibel.

K u \u003d U 2 / U 1 Voltage gain; K u [dB] = 20 log U 2 / U 1 Voltage gain in decibels. Ki [dB] = 20 log I 2 / I 1 Current gain in decibels. Kp[dB] = 10 log P 2 / P 1 Power gain in decibels.

The logarithmic scale also allows, on a graph of normal sizes, to depict functions that have a dynamic range of parameter changes in several orders of magnitude.

To determine the signal strength in the reception area, another logarithmic unit of DBM is used - dicibells per meter. Signal strength at the receiving point in dbm:

P [dbm] = 10 log U 2 / R +30 = 10 log P + 30. [dbm];

The effective load voltage at a known P[dBm] can be determined by the formula:

Dimensional coefficients of basic physical quantities

In accordance with state standards, the following multiple and submultiple units - prefixes are allowed:

Table 1 . Basic unit Voltage U Volt Current Ampere Resistance R, X Ohm Power P Watt Frequency f Hertz Inductance L Henry Capacity C Farad Dimensional coefficient T=tera=10 12 - - Volume - THz - - G=giga=10 9 GV GA GOM GW GHz - - M=mega=10 6 MV MA MOhm MW MHz - - K=kilo=10 3 HF KA KOM kW kHz - - 1 IN A Ohm Tue Hz gn F m=milli=10 -3 mV mA mΩ mW MHz mH mF mk=micro=10 -6 uV uA uO µW - µH uF n=nano=10 -9 nV on - nW - nH nF n=pico=10 -12 pv pA - pvt - pgn pF f=femto=10 -15 - - - fw - - FF a=atto=10 -18 - - - aW - - -

• Responsible for classifier support: Rostekhregulirovanie
• Reason: Decree of the State Standard of Russia dated 12/26/1994 No. 366 01/01/1996
• Approved: 06/07/2000
• Entered into force: 06/07/2000

Code	Name of the unit of measurement	Symbol		Symbol designation
		national	international	national	international
International units of measure included in the ESQM
Units of length
47	Nautical mile (1852 m)	mile	n mile	MILES	NMI
8	Kilometer; thousand meters	km; 10^3 m	km	KM; THOUSAND M	KMT
5	Decimeter	dm	dm	DM	DMT
4	Centimeter	cm	cm	CM	CMT
39	Inch (25.4mm)	inch	in	INCH	INH
6	Meter	m	m	M	MTR
41	Foot (0.3048 m)	foot	ft	FOOT	FOT
3	Millimeter	mm	mm	MM	MMT
9	Megameter; million meters	Mm; 10^6 m	mm	MEGAM; MLN M	MAM
43	Yard (0.9144 m)	yard	yd	YARD	YRD
area units
59	Hectare	ha	ha	GA	HAR
73	Square foot (0.092903 m2)	ft2	ft2	FUT2	FTK
53	square decimeter	dm2	dm2	DM2	DMK
61	Square kilometer	km2	km2	KM2	KMK
51	square centimeter	cm2	cm2	CM2	CMK
109	Ar (100 m2)	A	a	AR	ARE
55	Square meter	m2	m2	M2	MTK
58	Thousand square meters	10^3 m^2	daa	THOUSAND M2	DAA
75	Square yard (0.8361274 m2)	yard2	yd2	YARD2	YDK
50	square millimeter	mm2	mm2	MM2	MMK
71	Square inch (645.16 mm2)	inch2	in2	INCH2	INK
Volume units
126	Megaliter	ml	ml	MEGAL	MAL
132	Cubic foot (0.02831685 m3)	ft3	ft3	FT3	FTQ
118	Deciliter	dl	dl	DL	DLT
133	Cubic yard (0.764555 m3)	yard3	yd3	YARD3	YDQ
112	Liter; cubic decimeter	l; dm3	I; L; dm^3	L; DM3	LTR; DMQ
113	Cubic meter	m3	m3	M3	MTQ
131	Cubic inch (16387.1 mm3)	inch3	in3	INCH3	INQ
159	Million cubic meters	10^6 m3	10^6 m3	MN M3	HMQ
110	cubic millimeter	mm3	mm3	MM3	MMQ
122	Hl	ch	hl	GL	HLT
111	Cubic centimeter; milliliter	cm3; ml	cm3; ml	CM3; ML	CMQ; MLT
Mass units
170	Kiloton	10^3 t	kt	CT	KTN
161	Milligram	mg	mg	MG	MGM
173	centigram	sg	cg	SG	CGM
206	Centner (metric) (100 kg); hectokilogram; quintal1 (metric); deciton	c	q; 10^2kg	C	DTN
163	Gram	G	g	G	GRM
181	Gross register ton (2.8316 m3)	BRT	-	BRUTT. REGISTER T	GRT
160	Hectogram	gg	hg	GG	HGM
168	Ton; metric ton (1000 kg)	T	t	T	TNE
162	Metric carat	car	MS	CAR	CTM
185	Capacity in metric tons	t hydraulic fracturing	-	T LOAD	CCT
166	Kilogram	kg	kg	KG	KGM
Engineering units
331	Revolution per minute	rpm	r/min	RPM	RPM
300	Physical atmosphere (101325 Pa)	atm	atm	ATM	ATM
306	Gram of fissile isotopes	g D/I	fissile isotopes	G fissile isotope	GFI
304	Millicuri	mCi	mCi	MKI	MCU
243	watt hour	Wh	W.h	W.H	WHR
309	Bar	bar	bar	BAR	BAR
301	Technical atmosphere (98066.5 Pa)	at	at	ATT	ATT
270	Pendant	Cl	C	CL	COU
288	Kelvin	K	K	TO	KEL
280	Degree Celsius	deg. C	deg. C	GRAD CELSIUS	cel
282	Candela	cd	cd	KD	CDL
330	Revolution per second	r/s	r/s	OB/S	RPS
297	Kilopascal	kPa	kPa	CPA	KPA
302	Gigabecquerel	GBq	GBq	GIGABC	GBQ
291	KHz	kHz	kHz	CHC	KHZ
230	Kilovar	kvar	kvar	KVAR	KVR
281	Fahrenheit	deg. F	deg. F	GRAD FARENG	FAN
292	Megahertz	MHz	MHz	MEGAHZ	MHZ
227	Kilovolt-ampere	kVA	kV.A	KV.A	KVA
323	becquerel	Bq	bq	BC	BQL
298	Megapascal	MPa	MPa	MEGAPA	MPA
263	Ampere hour (3.6 kC)	Ah	A.h	A.Ch	AMH
247	Gigawatt hour (million kilowatt hours)	GWh	GW.h	GIGAW.H	GWH
245	Kilowatt hour	kWh	kWh	kWh	KWH
212	Watt	Tue	W	WT	WTT
273	Kilojoule	kJ	kJ	KJ	KJO
305	Curie	Key	Ci	CI	CUR
228	Megavolt-ampere (thousand kilovolt-amperes)	MV.A	MV.A	MEGAV.A	MVA
314	Farad	F	F	F	FAR
284	Lumen	lm	lm	LM	LUM
215	Megawatt; thousand kilowatts	MW; 10^3 kW	MW	MEGAVT; THOUSAND KW	MAW
274	Ohm	Ohm		OM	OHM
271	Joule	J	J	J	JOU
333	Kilometer per hour	km/h	km/h	km/h	KMH
349	pendant per kilogram	C/kg	C/kg	CL/KG	CKG
264	Thousand Ah	10^3 Ah	10^3 A.h	THOUSAND A.CH	TAH
222	Volt	IN	V	IN	VLT
223	Kilovolt	kV	kV	HF	KVT
335	Meter per second squared	m/s2	m/s2	M/S2	MSK
290	Hertz	Hz	Hz	HZ	H.T.Z.
260	Ampere	A	A	A	AMP
246	Megawatt-hour; 1000 kilowatt hours	MWh; 10^3 kWh	MW.h	MEGAW.CH; THOUSAND KWh	MWH
324	Weber	wb	wb	WB	WEB
312	Kilobar	kb	kbar	KBAR	KBA
294	Pascal	Pa	Pa	PA	PAL
283	Suite	OK	lx	OK	LUX
310	hectobar	gb	hbar	GBAR	HBA
308	Millibar	mb	mbar	MBAR	MBR
327	Knot (mile/h)	bonds	kn	UZ	KNT
296	Siemens	Cm	S	SI	SIE
316	kilogram per cubic meter	kg/m3	kg/m3	KG/M3	KMQ
328	Meter per second	m/s	m/s	M/S	MTS
214	Kilowatt	kW	kW	KBT	KWT
289	newton	H	N	H	NEW
Time units
368	Decade	deslet	-	DESLET	DEC
361	Decade	dec	-	DEC	DAD
364	Quarter	quart	-	QUART	QAN
365	half year	six months	-	HALF A YEAR	SAN
362	Month	months	-	MES	MON
359	Day	day; days	d	SUT; DN	DAY
355	Minute	min	min	MIN	MIN
356	Hour	h	h	H	HUR
360	A week	weeks	-	WED	WEE
354	Second	With	s	WITH	SEC
366	Year	G; years	a	YEAR; YEARS	ANN
Economic units
745	Element	elem	CI	ELEM	NCL
781	One hundred packs	100 pack	-	100 UPAK	CNP
732	ten couples	10 pairs	-	DES PAR	TPR
599	Thousand cubic meters per day	10^3 m3/day	-	THOUSAND M3/DAY	TQD
730	Two dozen	20	20	2 DES	SCO
733	a dozen couples	a dozen couples	-	A DOZEN COUPLES	DPR
799	Million pieces	10^6 pcs	10^6	MILLION PCS	MIO
796	Thing	PC	pc; 1	PC	PCE; NMB
778	Package	pack	-	UPAK	NMP
831	Liter of pure (100%) alcohol	l 100% alcohol	-	L PURE ALCOHOL	LPA
657	Product	ed	-	ED	NAR
865	kilogram of phosphorus pentoxide	kg Р2О5	-	KG PHOSPHORUS PENTOXIDE	KPP
641	Dozen (12 pcs.)	dozen	Doz; 12	DOZEN	DZN
841	Kilogram of hydrogen peroxide	kg H2O2	-	KG HYDROGEN PEROXIDE	-
734	Package	message	-	MESSAGE	NPL
704	Kit	kit	-	KIT	SET
847	Ton of 90% dry matter	t 90% s / w	-	T 90 PERC DRY	TSD
499	kilogram per second	kg/s	-	KG/S	KGS
801	Billion pieces (Europe); trillion pieces	10^12 pcs	10^12	BILL PCS (EUR); TRILL PC	BIL
683	One hundred boxes	100 boxes	hbx	100 boxes	HBX
740	a dozen pieces	dozen pcs	-	A DOZEN PCS	DPC
802	Quintillion pieces (Europe)	10^18 pcs	10^18	QUINT PC	TRL
821	Alcohol strength by volume	crepe. alcohol by volume	%vol	CREPES ALCOHOL BY VOLUME	ASV
533	Ton of steam per hour	t steam/h	-	T PAR/H	TSH
859	Kilogram of potassium hydroxide	kg KOH	-	KG POTASSIUM HYDROXIDE	KPH
852	Kilogram of potassium oxide	kg K2O	-	KG POTASSIUM OXIDE	KPO
625	Sheet	l.	-	SHEET	LEF
798	thousand pieces	thousand pieces; 1000 pcs	1000	THOUSAND PCS	MIL
630	Thousand standard conditional bricks	thousand std. conv. kirp	-	THOUSAND STAND CONDITIONS KIRP	MBE
797	One hundred pieces	100 pieces	100	100 PIECES	CEN
626	One hundred sheets	100 l.	-	100 SHEETS	CLF
736	Roll	rudder	-	RUL	NPL
780	Dozen packs	dozen pack	-	DOZEN PACK	DZP
800	Billion pieces	10^9 pcs	10^9	BILLION PCS	MLD
863	Kilogram of sodium hydroxide	kg NaOH	-	KG SODIUM HYDROXIDE	KSH
833	Hectoliter of pure (100%) alcohol	hl 100% alcohol	-	GL PURE ALCOHOL	HPA
715	Pair (2 pieces)	steam	pr; 2	STEAM	NPR
861	Kilogram of nitrogen	kg N	-	KG NITROGEN	KNI
598	cubic meter per hour	m3/h	m3/h	M3/H	MQH
845	Kilogram 90% dry matter	kg 90% w/w	-	KG 90 PER C DRY	KSD
867	Kilogram of uranium	kg U	-	KG URAN	KUR
735	Part	Part	-	PART	NPT
820	Alcohol strength by weight	crepe. alcohol by weight	%mds	CREPES ALCOHOL BY WEIGHT	ASM
737	Dozen rolls	a dozen rolls	-	DOZEN RUL	DRL
616	Spool	bean	-	BEAN	NBB
596	cubic meter per second	m3/s	m3/s	M3/S	MQS
National units of measure included in ESQM
Units of length
49	Kilometer of conditional pipes	km cond. pipes		KM USL PIPE
20	Conventional meter	conv. m		USL M
48	Thousand conventional meters	10^3 arb. m		THOUSAND CONVENTION M
18	Linear meter	linear m		POG M
19	Thousand running meters	10^3 line m		THOUSAND POG M
area units
57	Million square meters	10^6 m2		MN M2
81	Square meter of total area	m2 total pl		M2 GENERAL PL
64	One million conditional square meters	10^6 arb. m2		mln conv m2
83	Million square meters of total area	10^6 m2 total pl		MLN M2. TOTAL PL
62	Conditional square meter	conv. m2		USL M2
63	Thousand conditional square meters	10^3 arb. m2		THOUSAND CONVENTIONS M2
86	Million square meters of living space	10^6 m2 lived. pl		MLN M2 LIVE PL
82	Thousand square meters of total area	10^3 m2 total pl		THOUSAND M2 TOTAL PL
56	Million square decimeters	10^6 dm2		MN DM2
54	Thousand square decimeters	10^3 dm2		THOUSAND DM2
89	Million square meters in two-millimeter terms	10^6 m2 2 mm exc		MLN M2 2MM ISC
60	Thousand hectares	10^3 ha		THOUSAND HA
88	Thousand square meters of educational and laboratory buildings	10^3 m2 account. lab. building		THOUSAND M2 ACC. LAB ZDAN
87	Square meter of educational and laboratory buildings	m2 account. lab. building		M2 UCH.LAB BUILDING
85	Thousand square meters of living space	10^3 m2 lived. pl		THOUSAND M2 LIVES
84	square meter of living space	m2 lived. pl		M2 ZHIL PL
Volume units
121	dense cubic meter	dense m3		PLOTN M3
124	Thousand conditional cubic meters	10^3 arb. m3		THOUSAND CONVENTIONS M3
130	Thousand liters; 1000 liters	10^3 l; 1000 l		YOU SL
120	Million decaliters	10^6 dcl		MILLION DKL
129	Million half liters	10^6 Pos. l		MILLION POL L
128	One thousand half liters	10^3 Pos. l		THOUSAND POL L
123	Conventional cubic meter	conv. m3		USL M3
127	Thousand dense cubic meters	10^3 density m3		THOUSAND DENSITY M3
116	decalitre	dcl		DKL
114	Thousand cubic meters	10^3 m3		THOUSAND M3
115	Billion cubic meters	10^9 m3		BILLION M3
119	Thousand deciliters	10^3 dcl		THOUSAND DKL
125	Million cubic meters of gas processing	10^6 m3 recycled gas		MN M3 GAS PROCESSING
Mass units
167	Million carats metric	10^6 ct		MILLION CARS
178	Thousand tons of processing	10^3 t processed		THOUSAND T PROCESSED
176	Million tons of reference fuel	10^6 t conv. fuel		MN T FUEL
179	Conditional ton	conv. T		USL T
207	Thousand centners	10^3 z		THOUSAND C
171	Million tons	10^6 t		MN T
177	One thousand tons of one-time storage	10^3 tons at a time storage		THOUSAND UNIT STORAGE
169	Thousand tons	10^3 t		THOUSAND T
165	Thousand carats metric	10^3 ct		THOUSAND CARS
175	Thousand tons of reference fuel	10^3 t conv. fuel		THOUSAND T COND. FUEL
172	Ton of reference fuel	t conv. fuel		T CONDITION FUEL
Engineering units
226	Volt-ampere	V.A		V.A
339	Centimeter of water column	see aq. st		SM WOD ST
236	Calorie per hour	cal/h		cal/h
255	Byte	buy		BYTE
287	Henry	gn		GN
250	Thousand kilovolt-ampere reactive	10^3 kVA R		THOUSAND SQ.A R
235	One million gigacalories	10^6 Gcal		MILLION GIGAKAL
313	Tesla	Tl		TL
256	Kilobyte	kb		KBITE
234	Thousand gigacalories	10^3 Gcal		THOUSAND GIGACAL
237	kilocalorie per hour	kcal/h		Kcal/h
239	One thousand gigacalories per hour	10^3 Gcal/h		THOUSAND GIGACAL/H
317	kilogram per square centimeter	kg/cm^2		KG/CM2
252	Thousand horsepower	10^3 l. With		THOUSAND HP
238	Gigacalorie per hour	Gcal/h		GIGACAL/H
338	millimeter of mercury	mmHg st		MMHG
337	millimeter of water column	mm w.c. st		MM WOD ST
251	Horsepower	l. With		LS
258	Baud	baud		BAUD
242	Million kilovolt-amperes	10^6 kVA		MN SQA
232	Kilocalorie	kcal		KKAL
257	Megabyte	MB		MB
249	Billion kilowatt hours	10^9 kWh		BILLION kWh
241	Million Ah	10^6 Ah		MLN Ah
233	Gigacalorie	Gcal		GIGAKAL
253	A million horsepower	10^6 l. With		MLN drugs
231	Meter per hour	m/h		M/H
254	Bit	bit		BIT
248	Kilovolt-ampere reactive	kVA R		KV.A R
Time units
352	Microsecond	ms		ISS
353	Millisecond	mls		MLS
Economic units
534	ton per hour	t/h		T/H
513	Autoton	auto t		AUTO T
876	Conventional unit	conv. units		CONDITION UNITS
918	Author's sheet	l. auth		LIST AVT
873	Thousand vials	10^3 flask		THOUSAND FLAC
903	Thousand student places	10^3 academic places		THOUSAND SEATS
870	Ampoule	ampoules		AMPUL
421	Passenger seat (passenger seats)	pass. places		PASS SEATS
540	man-day	person days		PEOPLE DAYS
427	Passenger traffic	pass.flow		PASS.FLOW
896	Family	families		FAMILIES
751	A thousand rolls	10^3 roll		THOUSAND RUL
951	Thousand car-(machine)-hours	10^3 vag (mach.h)		THOUSAND VAG (MASH).H
963	Reduced hour	h		REF.H
978	Channel ends	channel. conc		CHANNEL. END
975	Sugo-day	strictly. day		SUGO. SUT
967	Million ton miles	10^6 t. miles		MILLION T. MILES
792	Human	people		CHEL
547	Couple in shift	steam/shift		STEAM/CHANG
839	Set	set		COMPL
881	Conditional bank	conv. bank		USL BANK
562	A thousand spinning spindles	10^3 strands		THOUSAND STRAIGHT BELIEVE
909	Apartment	quart		QUART
644	Million units	10^6 u		MILLION U
922	Sign	sign		SIGN
877	Thousand conventional units	10^3 arb. units		THOUSAND CONDITIONS
960	Thousand car-ton-days	10^3 car.ton.days		THOUSAND VEHICLES.ton.days
954	Car-day	vag.day		VAG.SUT
761	Thousand Mills	10^3 camp		THOUSAND STAN
511	kilogram per gigacalorie	kg/Gcal		KG/GIGACAL
912	Thousand beds	10^3 beds		THOUSAND BEDS
980	One thousand dollars	10^3 dollar		THOUSAND DOLLAR
387	Trillion rubles	10^12 rub		TRILL RUB
908	Number	nom		NOM
968	Million Passenger Miles	10^6 pass. miles		MILLION PASS. MILES
962	Thousand car-place-days	10^3 car places days		THOUSAND VEHICLE SEATS DN
916	Conditional repairs per year	conv. rem/year		COND. REM/YEAR
895	A million conditional bricks	10^6 arb. kirp		MLN CONDITIONS
414	Passenger-kilometre	pass.km		PASS.KM
888	Thousand conditional boxes	10^3 arb. crate		THOUSAND REQUIREMENTS
699	A thousand places	10^3 seats		THOUSAND PLACES
522	Person per square kilometer	person/km2		PERSON/KM2
869	Thousand bottles	10^3 bottles		THOUSAND BUT
958	Thousand passenger miles	10^3 passenger miles		THOUSAND PASS.MILES
510	Gram per kilowatt hour	g/kW.h		G/KW.H
983	Sudo-day	court day		SUD.SUT
535	Ton per day	t/day		T/SUT
424	Million Passenger-Kilometers	10^6 pass. km		MILLION PASS.KM
907	Thousand seats	10^3 landings places		THOUSAND POSAD PLACES
965	Thousand kilometers	10^3 km		THOUSAND KM
538	Thousand tons per year	10^3 t/year		THOUSAND T/YEAR
546	Thousand visits per shift	10^3 visits/shifts		THOUSAND VISITS / CHANGE
775	Thousand tubes	10^3 tube		THOUSAND TUBE
961	Thousand car-hours	10^3 av.h		THOUSAND VEHICLES.H
537	Thousand tons per season	10^3 t/s		THOUSAND T/SEZ
449	ton-kilometer	t.km		T.KM
556	Thousand heads a year	10^3 goal/year		THOUSAND GOALS/YEAR
383	Ruble	rub		RUB
970	Million seat-miles	10^6 pass. places. miles		MILLION PASS. LOCATION MILES
921	Accounting and publishing sheet	l. uch.-ed		LIST OF EDUCATION
894	Thousand conditional bricks	10^3 arb. kirp		THOUSAND CONDITIONS KIRP
514	Ton of thrust	t. thrust		T ROD
388	Quadrillion rubles	10^15 rub		SQUARE RUB
541	Thousand man-days	10^3 person days		THOUSAND PEOPLE DAYS
971	feed day	feed. days		FEED. DN
953	Thousand place-kilometers	10 ^3 local km		THOUSAND LOCATION.KM
871	Thousand ampoules	10^3 ampoules		THOUSAND AMPOULES
385	One million rubles	10^6 rub		MILLION RUB
966	Thousand tonnage flights	10^3 tonnage. flight		THOUSAND TONNAGE. FLIGHT
911	bunk	beds		KOEK
892	Thousand conditional tiles	10^3 arb. slabs		THOUSAND CONVENTIONAL PLATES
868	Bottle	but		BUT
793	Thousand people	10^3 people		THOUSAND PEOPLE
544	Million units per year	10^6 units/year		MLN U/YEAR
949	One million sheets	10^6 sheets.print		MILLION SHEET PRINTS
886	A million conditional pieces	10^6 arb. cous		MLN COND.
698	Place	places		PLACES
536	ton per shift	t/shift		T/CHANGE
548	Thousand pairs per shift	10^3 pairs/shifts		THOUSAND PAIRS/CHANGES
812	Box	crate		DR
915	Conditional repair	conv. rem		CONVENTION REM
956	Thousand train kilometers	10^3 train.km		THOUSAND TRAIN.KM
553	Thousand tons of processing per day	10^3 t processed / day		THOUSAND T PROCESSED/DAY
450	Thousand ton-kilometers	10^3 t.km		THOUSAND T.KM
950	Carriage (machine)-day	vag (mash).dn		VAG (MASH).DN
552	Ton processed per day	t processed/day		T PROCESS/DAY
423	Thousand passenger kilometers	10^3 pass.km		THOUSAND PASS.KM
924	Symbol	symbol		SYMBOL
782	Thousand Pack	10^3 pack		THOUSAND PACK
838	A million couples	10^6 pairs		MILLION PAIRS
905	A thousand jobs	10^3 work places		THOUSAND WORK PLACES
744	Percent	%		PROC
887	Conditional box	conv. crate		CONVENTION BOX
639	Dose	doses		DOS
891	Conditional tile	conv. slabs		CONVENTION PLATES
545	Visit on shift	visit/shift		ATTEND/CHANGE
543	Thousand conditional cans per shift	10^3 arb. bank / change		THOUSAND CONVENTION BANK/SCHANG
893	Conditional brick	conv. kirp		CONV KIRP
957	Thousand ton miles	10^3 t. miles		THOUSAND T.MILES
977	Channel-kilometer	channel. km		CHANNEL. KM
901	Million households	10^6 household		MILLION HOUSEHOLDS
976	Pieces in 20-foot equivalent (TEU)	pieces in 20-foot equivalent		PCS IN 20 FT EQUIV
762	Station	station		STANZ
897	Thousand families	10^3 families		THOUSAND FAMILIES
880	Thousand conditional pieces	10^3 arb. PC		THOUSAND CONVENTIONAL PCS
923	Word	word		WORD
955	Thousand train-hours	10^3 train.h		THOUSAND TRAIN.H
539	man-hour	pers.h		PERSONS
661	Channel	channel		CHANNEL
874	Thousand tubes	10^3 tubes		THOUSAND TUBE
558	Thousand bird places	10^3 bird places		THOUSAND BIRDS
913	Book fund volume	book volume. fund		VOLUME BOOK FUND
673	Thousand sets	10^3 sets		THOUSAND SET
640	A thousand doses	10^3 doses		THOUSAND DOSES
643	Thousand units	10^3 units		THOUSAND UNITS
878	One million conventional units	10^6 arb. units		MILLION CONDITIONS
914	Thousand volumes of the book fund	Volume 10^3 book. fund		THOUSAND VOLUME BOOK FUND
883	One million conditional cans	10^6 arb. bank		MLN USL BANK
384	Thousand rubles	10^3 rub		THOUSAND ROUBLES
925	Conditional pipe	conv. pipes		CONDITION PIPE
889	Conditional coil	conv. cat		CONVENTION CAT
900	Thousand households	10^3 household		THOUSAND DOMHOZ
898	Million Families	10^6 families		MILLION FAMILIES
964	Aircraft-kilometre	plane.km		SAMOLET.KM
979	One thousand copies	10^3 copies		THOUSAND SKU
746	Per mille (0.1 percent)	ppm		PROMILLE
890	Thousand conditional coils	10^3 arb. cat		THOUSAND CAT
724	Thousand hectares of portions	10^3 ha servings		THOUSAND HA PORTS
542	Thousand man-hours	10^3 pers.h		THOUSAND PEOPLE-H
642	Unit	units		ED
560	Minimal salary	min. wages boards		MIN WAGE
557	Million heads per year	10^6 head/year		MILLION GOALS/YEAR
917	Change	shifts		CHANGE
902	student place	scientist places		LEARNING LOCATIONS
521	person per square meter	person/m2		PEOPLE/M2
479	Thousand sets	10^3 set		THOUSAND SET
899	The household	household		DOMHOZ
906	seat	Posad. places		POSAD PLACES
515	Deadweight ton	dwt		DWT.T
982	Million tons of feed units	10^6 feed units		MN T FEED UNITS
959	car-day	car days		AUTO DN
972	Centner of feed units	c feed unit		C FEED ED
882	Thousand conditional jars	10^3 arb. bank		THOUSAND USL BANK
969	Million tonnage miles	10^6 tonnage. miles		MILLION TONNAGE. MILES
837	Thousand Pairs	10^3 pairs		THOUSAND PAIRS
810	Cell	cell		YACH
516	Tonno-tanid	t.tanid		T.TANID
794	Million people	10^6 people		MILLION PEOPLE
451	Million ton-kilometers	10^6 t. km		MLN T.KM
836	Head	Goal		GOAL
872	Bottle	flak		FLAC
808	One million copies	10^6 copies		MLN EPC
561	A thousand tons of steam per hour	10^3 t steam/h		THOUSAND STEAM/H
973	Thousand vehicle kilometers	10^3 cars km		THOUSAND VEHICLES KM
981	Thousand tons of feed units	10^3 feed units		THOUSAND T FEED UNITS
386	Billion rubles	10^9 rub		BILLION RUB
554	Centner of processing per day	c processed/day		C PROCESS/DAY
885	A thousand conditional pieces	10^3 arb. cous		THOUSAND CONDITIONS KUS
937	A million doses	10^6 doses		MILLION DOSES
920	Printed sheet	l. oven		PRINT SHEET
779	Million packs	10^6 pack		MLN UPAK
709	Thousand numbers	10^3 nom		THOUSAND NOM
512	Ton number	t.nom		T.NOM
952	Thousand wagon-(machine)-kilometers	10^3 vag (mach.km)		THOUSAND VAG (MASH).KM
879	Conditional piece	conv. PC		USL PC
904	Workplace	slave. places		WORK SEATS
559	Thousand laying hens	10^3 chickens. nesush		THOUSAND HENS. NESUSH
840	Section	section		SECC
974	Thousand tonnage-days	10^3 tonnage. day		THOUSAND TONNAGE. SUT
729	Thousand Pack	10^3 pack		THOUSAND PACH
910	Thousand apartments	10^3 qt		THOUSAND QUARTERS
550	Million tons per year	10^6 t/year		MN T/YEAR
875	Thousand boxes	10^3 kor		THOUSAND KOR
563	A thousand spinning places	10^3 strands		THOUSANDS OF PLACES
776	Thousand conditional tubes	10^3 conventional tubes		THOUSAND CONV. TUBE
884	Conditional piece	conv. cous		USL KUS
930	A thousand plates	10^3 layer		THOUSAND PLAST
555	Thousand centners of processing per day	10^3 q rework/day		THOUSAND C PROCESSED/DAY
International units of measurement not included in the EQMS
Units of length
17	Hectometer		hm		HMT
45	Mile (statutory) (1609.344 m)		miles		SMI
area units
79	square mile		miles2		MIK
77	Acre (4840 square yards)		acre		ACR
Volume units
137	Pint SC (0.568262 dm3)		pt (UK)		PTI
141	US fluid ounce (29.5735 cm3)		fl oz (US)		OZA
149	US dry gallon (4.404884 dm3)		dry gal (US)		GLD
153	Cord (3.63 m3)		-		WCD
152	Standard		-		WSD
145	US liquid gallon (3.78541 dm3)		gal (US)		GLL
154	Thousand board feet (2.36 m3)		-		MBF
143	US liquid pint (0.473176 dm3)		liq pt (US)		PTL
150	US bushel (35.2391 dm3)		bu (US)		BUA
136	Jill SK (0.142065 dm3)		gill (UK)		GII
144	US liquid quart (0.946353 dm3)		liq qt (US)		QTL
138	Quart UK (1.136523 dm3)		qt (UK)		QTI
135	Fluid ounce SK (28.413 cm3)		fl oz (UK)		OZI
139	Gallon SC (4.546092 dm3)		gal (UK)		GLI
148	US dry qt (1.101221 dm3)		dry qt (US)		QTD
140	Bushel UK (36.36874 dm3)		bu (UK)		BUI
151	US dry barrel (115.627 dm3)		bbl (US)		BLD
142	Jill USA (11.8294 cm3)		gill (US)		GIA
147	US dry pint (0.55061 dm3)		dry pt (US)		PTD
146	Barrel (petroleum) US (158.987 dm3)		barrel (US)		BLL
Mass units
184	Displacement		-		DPT
193	Centner US (45.3592 kg)		cwt		CWA
190	Stone SK (6.350293 kg)		st		STI
189	Gran UK US (64.798910 mg)		gn		GRN
200	US Drachma (3.887935 g)		-		DRA
194	Long hundredweight SK (50.802345 kg)		cwt (UK)		CWI
191	Quarter SK (12.700586 kg)		qtr		QTR
186	Pound UK, US (0.45359237 kg)		lb		LBR
187	Ounce UK, US (28.349523 g)		oz		ONZ
197	Scrooule SC, USA (1.295982 g)		scr		SCR
182	Net register ton		-		NTT
202	US troy pound (373.242 g)		-		LBT
201	Ounce UK, US (31.10348 g); troy ounce		apoz		APZ
196	Long ton SK, USA (1.0160469 t)		lt		LTN
188	Drachma SK (1.771745 g)		dr		DRI
183	Measured (freight) ton		-		SHT
198	Pennyweight UK, USA (1.555174 g)		dwt		DWT
192	Central SK (45.359237 kg)		-		CNT
195	Short ton SK, USA (0.90718474 t)		sht		STN
199	Drachma SK (3.887935 g)		drm		DRM
Engineering units
275	British thermal unit (1.055 kJ)		btu		BTU
213	Effective power (245.7 watts)		B.h.p.		BHP
Economic units
638	Gross (144 pcs.)		gr; 144		GRO
853	One hundred international units		-		HIU
835	Gallon of alcohol of the established strength		-		PGL
851	International unit		-		NIU
731	Big Gross (12 Gross)		1728		GGR
738	Short standard (7200 units)		-		SST

What is OKEI

OKEI is the abbreviation for the All-Russian Classification of Units of Measurement. The classifier is part of the Unified Coding and Classification System for Social and Technical and Economic Information in Russia. The All-Russian classifier of units of measurement was introduced on the territory of Russia instead of the All-Union classifier, known as the "System of designations of units and measurements used in automated control systems." A classifier has been developed based on the international classification of measurement units of the UN Economic European Commission, the Commodity Nomenclature for Foreign Economic Activity and other significant documents. The all-Russian classifier of units of measurement is associated with GOST 8.417-81 "State system for ensuring the uniformity of measurements. Units of physical quantities".

Why was OKEI created?

The classifier is intended for use in solving problems of quantitative assessment of social and technical and economic indicators for state reporting and accounting, forecasting and economic development, foreign and domestic trade, providing statistical international comparisons, organizing customs control, regulating foreign economic activity. In OKEI, classification objects are units of measurement that are used in these areas of activity.

What is the code structure in OKEI

In OKEI, units of measurement are divided into 7 groups: units of length, area, volume, mass, technical units and units of time, as well as economic units. For a number of units of measurement, submultiples and multiples have been introduced. The All-Russian classifier of units of measurement contains two reference appendices and two sections.

Each position in OKEI structurally consists of three blocks: identification, name and block, where additional features are indicated.

The identification code of the unit of measurement is a digital three-digit decimal code, which was assigned according to the serial-order coding system. In Annex A and the first section, codes are used that completely coincide with the codes of the international classification. Also in the second section, decimal three-digit codes were used, taken from the reserve of international classification codes.

In OKEI, the formula for the structure of the identification code is as follows: XXX. The name block is the name of the unit of measurement adopted in state reporting and accounting (for the second section), or the name of the unit of measurement according to the international classification (for Appendix A and the first section). The block of additional features is conditional data, letter codes for units of measurement (national and international).

In order to facilitate the use of the classifier, an alphabetical index of units of measurement is given in Appendix B. In the second column, the number of the application or section in which the unit of measurement is located is indicated. The third column is the identification code of the unit of measurement.

The maintenance of the All-Russian classifier of units of measurement is carried out by VNIIKI of the State Standard of the Russian Federation together with the Computing Center of the State Statistics Committee of the Russian Federation, the Center for Economic Conjuncture under the Government of Russia.

In principle, one can imagine any number of different systems of units, but only a few have become widespread. All over the world, for scientific and technical measurements, and in most countries in industry and everyday life, the metric system is used.

Basic units.

In the system of units for each measured physical quantity, an appropriate unit of measurement must be provided. Thus, a separate unit of measure is needed for length, area, volume, speed, etc., and each such unit can be determined by choosing one or another standard. But the system of units turns out to be much more convenient if in it only a few units are chosen as the main ones, and the rest are determined through the main ones. So, if the unit of length is a meter, the standard of which is stored in the State Metrological Service, then the unit of area can be considered a square meter, the unit of volume is a cubic meter, the unit of speed is a meter per second, etc.

The convenience of such a system of units (especially for scientists and engineers, who are much more likely to deal with measurements than other people) is that the mathematical relationships between the basic and derived units of the system turn out to be simpler. At the same time, a unit of speed is a unit of distance (length) per unit of time, a unit of acceleration is a unit of change in speed per unit of time, a unit of force is a unit of acceleration per unit of mass, etc. In mathematical notation, it looks like this: v = l/t, a = v/t, F = ma = ml/t 2. The presented formulas show the "dimension" of the quantities under consideration, establishing relationships between units. (Similar formulas allow you to define units for quantities such as pressure or electric current.) Such relationships are general and hold regardless of which units (meter, foot, or arshin) are measured in length and which units are chosen for other quantities.

In engineering, the basic unit of measurement of mechanical quantities is usually taken not as a unit of mass, but as a unit of force. Thus, if in the system most used in physical research, a metal cylinder is taken as a standard of mass, then in a technical system it is considered as a standard of force that balances the force of gravity acting on it. But since the force of gravity is not the same at different points on the surface of the Earth, for the exact implementation of the standard, it is necessary to indicate the location. Historically, the location was taken at sea level at a geographic latitude of 45°. At present, such a standard is defined as the force necessary to give the indicated cylinder a certain acceleration. It is true that measurements in technology are, as a rule, not carried out with such a high accuracy that it would be necessary to take care of variations in the force of gravity (if we are not talking about the calibration of measuring instruments).

A lot of confusion is associated with the concepts of mass, force and weight. The fact is that there are units of all these three quantities that have the same names. Mass is an inertial characteristic of a body, showing how difficult it is to be removed by an external force from a state of rest or uniform and rectilinear motion. A unit of force is a force that, acting on a unit of mass, changes its speed by a unit of speed per unit of time.

All bodies are attracted to each other. Thus, any body near the Earth is attracted to it. In other words, the Earth creates the force of gravity acting on the body. This force is called its weight. The force of weight, as mentioned above, is not the same at different points on the surface of the Earth and at different heights above sea level due to differences in gravitational attraction and in the manifestation of the rotation of the Earth. However, the total mass of a given amount of substance is unchanged; it is the same in interstellar space and at any point on Earth.

Precise experiments have shown that the force of gravity acting on different bodies (i.e. their weight) is proportional to their mass. Therefore, masses can be compared on a balance, and masses that are the same in one place will be the same in any other place (if the comparison is carried out in a vacuum to exclude the influence of the displaced air). If a certain body is weighed on a spring balance, balancing the force of gravity with the force of an extended spring, then the results of the weight measurement will depend on the place where the measurements are taken. Therefore, spring scales must be adjusted at each new location so that they correctly show the mass. The simplicity of the weighing procedure itself was the reason that the force of gravity acting on the reference mass was taken as an independent unit of measurement in technology. HEAT.

Metric system of units.

The metric system is the common name for the international decimal system of units, the basic units of which are the meter and the kilogram. With some differences in details, the elements of the system are the same all over the world.

Story.

The metric system grew out of the decrees adopted by the National Assembly of France in 1791 and 1795 to define the meter as one ten-millionth of the length of the earth's meridian from the North Pole to the equator.

By a decree issued on July 4, 1837, the metric system was declared mandatory for use in all commercial transactions in France. It has gradually supplanted local and national systems elsewhere in Europe and has been legally accepted in the UK and the US. An agreement signed on May 20, 1875 by seventeen countries created an international organization designed to preserve and improve the metric system.

It is clear that by defining the meter as a ten millionth of a quarter of the earth's meridian, the creators of the metric system sought to achieve invariance and exact reproducibility of the system. They took a gram as a unit of mass, defining it as the mass of one millionth of a cubic meter of water at its maximum density. Since it would not be very convenient to make geodetic measurements of a quarter of the earth's meridian with each sale of a meter of cloth or to balance a basket of potatoes in the market with an appropriate amount of water, metal standards were created that reproduce these ideal definitions with the utmost accuracy.

It soon became clear that metal standards of length could be compared with each other, introducing a much smaller error than when comparing any such standard with a quarter of the earth's meridian. In addition, it became clear that the accuracy of comparing metal mass standards with each other is much higher than the accuracy of comparing any such standard with the mass of the corresponding volume of water.

In this regard, the International Commission on the Meter in 1872 decided to take the “archival” meter stored in Paris “as it is” as the standard of length. Similarly, the members of the Commission took the archival platinum-iridium kilogram as the standard of mass, “considering that the simple ratio established by the creators of the metric system between a unit of weight and a unit of volume represents the existing kilogram with an accuracy sufficient for ordinary uses in industry and commerce, and accurate science needs not a simple numerical ratio of this kind, but an extremely perfect definition of this ratio. In 1875, many countries of the world signed an agreement on the meter, and this agreement established the procedure for coordinating metrological standards for the world scientific community through the International Bureau of Weights and Measures and the General Conference on Weights and Measures.

The new international organization immediately took up the development of international standards of length and mass and the transfer of their copies to all participating countries.

Length and mass standards, international prototypes.

International prototypes of standards of length and mass - meters and kilograms - were deposited with the International Bureau of Weights and Measures, located in Sevres, a suburb of Paris. The standard meter was a ruler made of an alloy of platinum with 10% iridium, the cross section of which was given a special X-shape to increase flexural rigidity with a minimum volume of metal. There was a longitudinal flat surface in the groove of such a ruler, and the meter was defined as the distance between the centers of two strokes applied across the ruler at its ends, at a standard temperature of 0 ° C. The mass of a cylinder made from the same platinum was taken as the international prototype of the kilogram. iridium alloy, which is the standard of the meter, with a height and diameter of about 3.9 cm. The weight of this standard mass, equal to 1 kg at sea level at a geographical latitude of 45 °, is sometimes called a kilogram-force. Thus, it can be used either as a standard of mass for the absolute system of units, or as a standard of force for the technical system of units, in which one of the basic units is the unit of force.

The International Prototypes were selected from a significant batch of identical standards made at the same time. The other standards of this batch were transferred to all participating countries as national prototypes (state primary standards), which are periodically returned to the International Bureau for comparison with international standards. Comparisons made at various times since then show that they show no deviations (from international standards) beyond the limits of measurement accuracy.

International SI system.

The metric system was very favorably received by scientists of the 19th century. partly because it was proposed as an international system of units, partly because its units were theoretically supposed to be independently reproducible, and also because of its simplicity. Scientists began to derive new units for the various physical quantities they were dealing with, based on the elementary laws of physics and relating these units to the units of length and mass of the metric system. The latter increasingly conquered various European countries, in which many unrelated units for different quantities were previously in circulation.

Although in all countries that adopted the metric system of units, the standards of metric units were almost the same, various discrepancies in derived units arose between different countries and different disciplines. In the field of electricity and magnetism, two separate systems of derived units have emerged: the electrostatic one, based on the force with which two electric charges act on each other, and the electromagnetic one, based on the force of the interaction of two hypothetical magnetic poles.

The situation became even more complicated with the advent of the so-called. practical electrical units, introduced in the middle of the 19th century. British Association for the Advancement of Science to meet the demands of rapidly developing wire telegraph technology. Such practical units do not coincide with the units of the two systems named above, but differ from the units of the electromagnetic system only by factors equal to integer powers of ten.

Thus, for such common electrical quantities as voltage, current and resistance, there were several options for accepted units of measurement, and each scientist, engineer, teacher had to decide for himself which of these options he should use. In connection with the development of electrical engineering in the second half of the 19th and first half of the 20th centuries. more and more practical units were used, which eventually came to dominate the field.

To eliminate such confusion in the early 20th century. a proposal was put forward to combine practical electrical units with the corresponding mechanical units based on metric units of length and mass, and to build some kind of consistent (coherent) system. In 1960, the XI General Conference on Weights and Measures adopted a unified International System of Units (SI), defined the basic units of this system and prescribed the use of some derived units, "without prejudice to the question of others that may be added in the future." Thus, for the first time in history, an international coherent system of units was adopted by international agreement. It is now accepted as the legal system of units of measurement by most countries in the world.

The International System of Units (SI) is a harmonized system in which for any physical quantity such as length, time or force, there is one and only one unit of measure. Some of the units are given specific names, such as the pascal for pressure, while others are named after the units from which they are derived, such as the unit of speed, the meter per second. The main units, together with two additional geometric ones, are presented in Table. 1. Derived units for which special names are adopted are given in Table. 2. Of all the derived mechanical units, the most important are the newton unit of force, the joule unit of energy, and the watt unit of power. Newton is defined as the force that gives a mass of one kilogram an acceleration equal to one meter per second squared. A joule is equal to the work done when the point of application of a force equal to one Newton moves one meter in the direction of the force. A watt is the power at which work of one joule is done in one second. Electrical and other derived units will be discussed below. The official definitions of primary and secondary units are as follows.

A meter is the distance traveled by light in a vacuum in 1/299,792,458 of a second. This definition was adopted in October 1983.

The kilogram is equal to the mass of the international prototype of the kilogram.

A second is the duration of 9,192,631,770 periods of radiation oscillations corresponding to transitions between two levels of the hyperfine structure of the ground state of the cesium-133 atom.

Kelvin is equal to 1/273.16 of the thermodynamic temperature of the triple point of water.

The mole is equal to the amount of a substance, which contains as many structural elements as there are atoms in the carbon-12 isotope with a mass of 0.012 kg.

A radian is a flat angle between two radii of a circle, the length of the arc between which is equal to the radius.

The steradian is equal to the solid angle with the vertex at the center of the sphere, which cuts out on its surface an area equal to the area of ​​a square with a side equal to the radius of the sphere.

For the formation of decimal multiples and submultiples, a number of prefixes and multipliers are prescribed, indicated in Table. 3.

Table 3 INTERNATIONAL SI DECIMAL MULTIPLES AND MULTIPLE UNITS AND MULTIPLIERS
exa			deci
peta			centi
tera			Milli
giga			micro	mk
mega			nano
kilo			pico
hecto			femto
soundboard	Yes		atto

Thus, a kilometer (km) is 1000 m, and a millimeter is 0.001 m. (These prefixes apply to all units, such as kilowatts, milliamps, etc.)

Initially, one of the basic units was supposed to be the gram, and this was reflected in the names of the units of mass, but now the basic unit is the kilogram. Instead of the name of megagrams, the word "ton" is used. In physical disciplines, for example, to measure the wavelength of visible or infrared light, a millionth of a meter (micrometer) is often used. In spectroscopy, wavelengths are often expressed in angstroms (Å); An angstrom is equal to one tenth of a nanometer, i.e. 10 - 10 m. For radiation with a shorter wavelength, such as x-rays, in scientific publications it is allowed to use a picometer and x-unit (1 x-unit = 10 -13 m). A volume equal to 1000 cubic centimeters (one cubic decimeter) is called a liter (l).

Mass, length and time.

All the basic units of the SI system, except for the kilogram, are currently defined in terms of physical constants or phenomena, which are considered to be invariable and reproducible with high accuracy. As for the kilogram, a method for its implementation with the degree of reproducibility that is achieved in the procedures for comparing various mass standards with the international prototype of the kilogram has not yet been found. Such a comparison can be carried out by weighing on a spring balance, the error of which does not exceed 1×10–8. The standards of multiples and submultiples for a kilogram are established by combined weighing on a balance.

Because the meter is defined in terms of the speed of light, it can be reproduced independently in any well-equipped laboratory. So, by the interference method, dashed and end gauges, which are used in workshops and laboratories, can be checked by comparing directly with the wavelength of light. The error with such methods under optimal conditions does not exceed one billionth (1×10–9). With the development of laser technology, such measurements have been greatly simplified and their range has been substantially extended.

Similarly, the second, in accordance with its modern definition, can be independently realized in a competent laboratory in an atomic beam facility. The beam atoms are excited by a high-frequency generator tuned to the atomic frequency, and the electronic circuit measures time by counting the oscillation periods in the generator circuit. Such measurements can be carried out with an accuracy of the order of 1×10 -12 - much better than was possible with previous definitions of the second, based on the rotation of the Earth and its revolution around the Sun. Time and its reciprocal, frequency, are unique in that their references can be transmitted by radio. Thanks to this, anyone with the appropriate radio receiving equipment can receive accurate time and reference frequency signals that are almost identical in accuracy to those transmitted on the air.

Mechanics.

temperature and warmth.

Mechanical units do not allow solving all scientific and technical problems without involving any other ratios. Although the work done when moving a mass against the action of a force and the kinetic energy of a certain mass are equivalent in nature to the thermal energy of a substance, it is more convenient to consider temperature and heat as separate quantities that do not depend on mechanical ones.

Thermodynamic temperature scale.

The thermodynamic temperature unit Kelvin (K), called the kelvin, is determined by the triple point of water, i.e. the temperature at which water is in equilibrium with ice and steam. This temperature is taken equal to 273.16 K, which determines the thermodynamic temperature scale. This scale, proposed by Kelvin, is based on the second law of thermodynamics. If there are two heat reservoirs with constant temperature and a reversible heat engine transferring heat from one of them to the other in accordance with the Carnot cycle, then the ratio of the thermodynamic temperatures of the two reservoirs is given by the equality T 2 /T 1 = –Q 2 Q 1 , where Q 2 and Q 1 - the amount of heat transferred to each of the reservoirs (the minus sign indicates that heat is taken from one of the reservoirs). Thus, if the temperature of the warmer reservoir is 273.16 K, and the heat taken from it is twice the heat transferred to another reservoir, then the temperature of the second reservoir is 136.58 K. If the temperature of the second reservoir is 0 K, then it no heat will be transferred at all, since all the energy of the gas has been converted into mechanical energy in the adiabatic expansion section of the cycle. This temperature is called absolute zero. The thermodynamic temperature commonly used in scientific research, coincides with the temperature included in the equation of state for an ideal gas PV = RT, Where P- pressure, V- volume and R is the gas constant. The equation shows that for an ideal gas, the product of volume and pressure is proportional to temperature. For any of the real gases, this law is not exactly fulfilled. But if we make corrections for virial forces, then the expansion of gases allows us to reproduce the thermodynamic temperature scale.

International temperature scale.

In accordance with the above definition, the temperature can be measured with a very high accuracy (up to about 0.003 K near the triple point) by gas thermometry. A platinum resistance thermometer and a gas reservoir are placed in a heat-insulated chamber. When the chamber is heated, the electrical resistance of the thermometer increases and the gas pressure in the tank rises (in accordance with the equation of state), and when cooled, the opposite is observed. By simultaneously measuring resistance and pressure, it is possible to calibrate a thermometer according to gas pressure, which is proportional to temperature. The thermometer is then placed in a thermostat in which liquid water can be maintained in equilibrium with its solid and vapor phases. By measuring its electrical resistance at this temperature, a thermodynamic scale is obtained, since the temperature of the triple point is assigned a value equal to 273.16 K.

There are two international temperature scales - Kelvin (K) and Celsius (C). The Celsius temperature is obtained from the Kelvin temperature by subtracting 273.15 K from the latter.

Accurate temperature measurements using gas thermometry require a lot of work and time. Therefore, in 1968 the International Practical Temperature Scale (IPTS) was introduced. Using this scale, thermometers of various types can be calibrated in the laboratory. This scale was established using a platinum resistance thermometer, a thermocouple and a radiation pyrometer used in the temperature intervals between some pairs of constant reference points (temperature reference points). The MTS was supposed to correspond with the greatest possible accuracy to the thermodynamic scale, but, as it turned out later, its deviations are very significant.

Fahrenheit temperature scale.

The Fahrenheit temperature scale, which is widely used in combination with the British technical system of units, as well as in non-scientific measurements in many countries, is usually determined by two constant reference points - the melting temperature of ice (32 ° F) and the boiling point of water (212 ° F) at normal (atmospheric) pressure. Therefore, to get the Celsius temperature from the Fahrenheit temperature, subtract 32 from the latter and multiply the result by 5/9.

Heat units.

Since heat is a form of energy, it can be measured in joules, and this metric unit has been adopted by international agreement. But since the amount of heat was once determined by changing the temperature of a certain amount of water, a unit called a calorie and equal to the amount of heat needed to raise the temperature of one gram of water by 1 ° C became widespread. Due to the fact that the heat capacity of water depends on temperature , I had to specify the value of the calorie. At least two different calories appeared - "thermochemical" (4.1840 J) and "steam" (4.1868 J). The “calorie” used in dieting is actually a kilocalorie (1000 calories). The calorie is not an SI unit and has fallen into disuse in most areas of science and technology.

electricity and magnetism.

All common electrical and magnetic units of measurement are based on metric system. In accordance with modern definitions of electrical and magnetic units, they are all derived units derived from certain physical formulas from metric units of length, mass and time. Since most electrical and magnetic quantities are not so easy to measure using the standards mentioned, it was considered that it was more convenient to establish, by appropriate experiments, derived standards for some of the indicated quantities, and measure others using such standards.

SI units.

Below is a list of electrical and magnetic units of the SI system.

The ampere, the unit of electric current, is one of the six basic units of the SI system. Ampere - the strength of an unchanging current, which, when passing through two parallel rectilinear conductors of infinite length with a negligible circular cross-sectional area, located in vacuum at a distance of 1 m from one another, would cause an interaction force equal to 2 × 10 on each section of the conductor 1 m long - 7 N.

Volt, unit of potential difference and electromotive force. Volt - electric voltage in a section of an electrical circuit with a direct current of 1 A with a power consumption of 1 W.

Coulomb, a unit of quantity of electricity (electric charge). Coulomb - the amount of electricity passing through the cross section of the conductor at a constant current of 1 A in a time of 1 s.

Farad, unit of electrical capacitance. Farad is the capacitance of a capacitor, on the plates of which, with a charge of 1 C, an electric voltage of 1 V arises.

Henry, unit of inductance. Henry is equal to the inductance of the circuit in which an EMF of self-induction of 1 V occurs with a uniform change in the current strength in this circuit by 1 A per 1 s.

Weber, unit of magnetic flux. Weber - a magnetic flux, when it decreases to zero in a circuit coupled to it, which has a resistance of 1 Ohm, an electric charge equal to 1 C flows.

Tesla, unit of magnetic induction. Tesla - magnetic induction of a uniform magnetic field, in which the magnetic flux through a flat area of ​​​​1 m 2, perpendicular to the lines of induction, is 1 Wb.

Practical standards.

Light and illumination.

The units of luminous intensity and illuminance cannot be determined on the basis of mechanical units alone. It is possible to express the energy flux in a light wave in W/m 2 and the intensity of a light wave in V/m, as in the case of radio waves. But the perception of illumination is a psychophysical phenomenon in which not only the intensity of the light source is essential, but also the sensitivity of the human eye to the spectral distribution of this intensity.

By international agreement, the candela (previously called a candle) is accepted as a unit of luminous intensity, equal to the luminous intensity in a given direction of a source emitting monochromatic radiation with a frequency of 540 × 10 12 Hz ( l\u003d 555 nm), the energy strength of the light radiation of which in this direction is 1/683 W / sr. This roughly corresponds to the light intensity of the spermaceti candle, which once served as a standard.

If the luminous intensity of the source is one candela in all directions, then the total luminous flux is 4 p lumens Thus, if this source is located in the center of a sphere with a radius of 1 m, then the illumination of the inner surface of the sphere is equal to one lumen per square meter, i.e. one suite.

X-ray and gamma radiation, radioactivity.

Roentgen (R) is an obsolete unit of exposure dose of X-ray, gamma and photon radiation, equal to the amount of radiation, which, taking into account secondary electron radiation, forms ions in 0.001 293 g of air, carrying a charge equal to one CGS charge unit of each sign. In the SI system, the unit of absorbed radiation dose is the gray, which is equal to 1 J/kg. The standard of the absorbed dose of radiation is the installation with ionization chambers, which measure the ionization produced by radiation.



Since 1963, in the USSR (GOST 9867-61 "International System of Units"), in order to unify units of measurement in all fields of science and technology, the international (international) system of units (SI, SI) has been recommended for practical use - this is a system of units for measuring physical quantities , adopted by the XI General Conference on Weights and Measures in 1960. It is based on 6 basic units (length, mass, time, electric current, thermodynamic temperature and light intensity), as well as 2 additional units (flat angle, solid angle) ; all other units given in the table are their derivatives. The adoption of a single international system of units for all countries is intended to eliminate the difficulties associated with translating the numerical values ​​of physical quantities, as well as various constants from any one currently operating system (CGS, MKGSS, ISS A, etc.), into another.

Value name	Units; SI values	Notation
		Russian	international
I. Length, mass, volume, pressure, temperature
	Meter - a measure of length, numerically equal to the length of the international standard of the meter; 1 m=100 cm (1 10 2 cm)=1000 mm (1 10 3 mm)	m	m
	Centimeter \u003d 0.01 m (1 10 -2 m) \u003d 10 mm	cm	cm
	Millimeter \u003d 0.001 m (1 10 -3 m) \u003d 0.1 cm \u003d 1000 microns (1 10 3 microns)	mm	mm
	Micron (micrometer) = 0.001 mm (1 10 -3 mm) = 0.0001 cm (1 10 -4 cm) = 10,000	mk	μ
	Angstrom = one ten billionth of a meter (1 10 -10 m) or one hundred millionth of a centimeter (1 10 -8 cm)	Å	Å
Weight	Kilogram - the basic unit of mass in the metric system of measures and the SI system, numerically equal to the mass of the international standard of the kilogram; 1 kg=1000 g	kg	kg
	Gram \u003d 0.001 kg (1 10 -3 kg)	G	g
	Ton = 1000 kg (1 10 3 kg)	T	t
	Centner \u003d 100 kg (1 10 2 kg)	c
	Carat - non-systemic unit of mass, numerically equal to 0.2 g		ct
	Gamma=one millionth of a gram (1 10 -6 g)		γ
Volume	Liter \u003d 1.000028 dm 3 \u003d 1.000028 10 -3 m 3	l	l
Pressure	Physical, or normal, atmosphere - pressure balanced by a mercury column 760 mm high at a temperature of 0 ° = 1.033 at = = 1.01 10 -5 n / m 2 = 1.01325 bar = 760 torr = 1.033 kgf / cm 2	atm	atm
	Technical atmosphere - pressure equal to 1 kgf / cmg \u003d 9.81 10 4 n / m 2 \u003d 0.980655 bar \u003d 0.980655 10 6 dynes / cm 2 \u003d 0.968 atm \u003d 735 torr	at	at
	Millimeter of mercury column \u003d 133.32 n / m 2	mmHg Art.	mm Hg
	Tor - the name of an off-system unit of pressure measurement, equal to 1 mm Hg. Art.; given in honor of the Italian scientist E. Torricelli	torus
	Bar - unit atmospheric pressure\u003d 1 10 5 n / m 2 \u003d 1 10 6 dynes / cm 2	bar	bar
Pressure (sound)	Bar-unit of sound pressure (in acoustics): bar - 1 dyne / cm 2; at present, a unit with a value of 1 n / m 2 \u003d 10 dynes / cm 2 is recommended as a unit of sound pressure	bar	bar
	The decibel is a logarithmic unit of measurement of the level of excess sound pressure, equal to 1/10 of the unit of measurement of excess pressure - white	dB	db
Temperature	Degree Celsius; temperature in °K (Kelvin scale), equal to temperature in °C (Celsius scale) + 273.15 °C	°С	°С
II. Force, power, energy, work, amount of heat, viscosity
Force	Dyna - a unit of force in the CGS system (cm-g-sec.), At which an acceleration equal to 1 cm / sec 2 is reported to a body with a mass of 1 g; 1 din - 1 10 -5 n	din	dyn
	Kilogram-force is a force imparting to a body with a mass of 1 kg an acceleration equal to 9.81 m / s 2; 1kg \u003d 9.81 n \u003d 9.81 10 5 din	kg, kgf
Power	Horsepower=735.5W	l. With.	HP
Energy	Electron-volt - the energy that an electron acquires when moving in an electric field in vacuum between points with a potential difference of 1 V; 1 ev \u003d 1.6 10 -19 j. Multiple units are allowed: kiloelectron-volt (Kvv) = 10 3 eV and megaelectron-volt (MeV) = 10 6 eV. In modern charged particle accelerators, the energy of particles is measured in BeV - billions (billions) eV; 1 Bzv=10 9 ev	ev	eV
	Erg=1 10 -7 j; erg is also used as a unit of work, numerically equal to the work done by a force of 1 dyne in a path of 1 cm	erg	erg
Job	Kilogram-force-meter (kilogrammeter) - a unit of work numerically equal to the work done by a constant force of 1 kg when the point of application of this force moves a distance of 1 m in its direction; 1kGm = 9.81 J (at the same time, kGm is a measure of energy)	kgm, kgf m	kgm
Quantity of heat	Calorie - an off-system unit for measuring the amount of heat equal to the amount of heat required to heat 1 g of water from 19.5 ° C to 20.5 ° C. 1 cal = 4.187 j; common multiple unit kilocalorie (kcal, kcal), equal to 1000 cal	feces	cal
Viscosity (dynamic)	Poise is a unit of viscosity in the CGS system of units; the viscosity at which a 1 dyne viscous force acts in a layered flow with a velocity gradient of 1 sec -1 per 1 cm 2 of the layer surface; 1 pz \u003d 0.1 n s / m 2	pz	P
Viscosity (kinematic)	Stokes is the unit of kinematic viscosity in the CGS system; equal to the viscosity of a liquid having a density of 1 g / cm 3, resisting a force of 1 dyne to the mutual movement of two layers of a liquid with an area of ​​\u200b\u200b1 cm 2 located at a distance of 1 cm from each other and moving relative to each other at a speed of 1 cm per second	st	St
III. Magnetic flux, magnetic induction, magnetic field strength, inductance, capacitance
magnetic flux	Maxwell - a unit of measurement of magnetic flux in the cgs system; 1 μs is equal to the magnetic flux passing through the area of ​​1 cm 2 located perpendicular to the lines of induction of the magnetic field, with an induction equal to 1 gauss; 1 μs = 10 -8 wb (Weber) - units of magnetic current in the SI system	ms	Mx
Magnetic induction	Gauss is a unit of measure in the cgs system; 1 gauss is the induction of such a field in which a rectilinear conductor 1 cm long, located perpendicular to the field vector, experiences a force of 1 dyne if a current of 3 10 10 CGS units flows through this conductor; 1 gs \u003d 1 10 -4 t (tesla)	gs	Gs
Magnetic field strength	Oersted - unit of magnetic field strength in the CGS system; for one oersted (1 e) the intensity at such a point of the field is taken, in which a force of 1 dyne (dyne) acts on 1 electromagnetic unit of the amount of magnetism; 1 e \u003d 1 / 4π 10 3 a / m	uh	Oe
Inductance	Centimeter - a unit of inductance in the CGS system; 1 cm = 1 10 -9 gn (henry)	cm	cm
Electrical capacitance	Centimeter - unit of capacitance in the CGS system = 1 10 -12 f (farads)	cm	cm
IV. Light intensity, luminous flux, brightness, illumination
The power of light	A candle is a unit of luminous intensity, the value of which is taken so that the brightness of a full emitter at the solidification temperature of platinum is 60 sv per 1 cm 2	St.	cd
Light flow	Lumen - a unit of luminous flux; 1 lumen (lm) is radiated over a solid angle of 1 stere by a point source of light that has a luminous intensity of 1 St in all directions.	lm	lm
	Lumen-second - corresponds to the light energy generated by a luminous flux of 1 lm, emitted or perceived in 1 second	lm s	lm sec
	Lumen hour equals 3600 lumen seconds	lm h	lm h
Brightness	Stilb is a unit of brightness in the cgs system; corresponds to the brightness of a flat surface, 1 cm 2 of which gives in the direction perpendicular to this surface, a luminous intensity equal to 1 ce; 1 sb \u003d 1 10 4 nt (nit) (unit of brightness in the SI system)	Sat	sb
	Lambert is an off-system unit of brightness, derived from the stilb; 1 lambert = 1/π st = 3193 nt
	Apostille = 1 / π St / m 2
illumination	Fot - unit of illumination in the SGSL system (cm-g-sec-lm); 1 ph corresponds to the surface illumination of 1 cm 2 with a uniformly distributed luminous flux of 1 lm; 1 f \u003d 1 10 4 lux (lux)	f	ph
V. Radiation intensity and doses
Radioactivity intensity	Curie is the basic unit for measuring the intensity of radioactive radiation, curie corresponding to 3.7·10 10 decays in 1 sec. any radioactive isotope	curie	C or Cu
	millicurie \u003d 10 -3 curie, or 3.7 10 7 acts of radioactive decay in 1 sec.	mcurie	mc or mCu
	microcurie = 10 -6 curie	microcurie	μC or μCu
Dose	X-ray - the amount (dose) of X-ray or γ-rays, which in 0.001293 g of air (i.e., in 1 cm 3 of dry air at t ° 0 ° and 760 mm Hg) causes the formation of ions that carry one electrostatic a unit of the amount of electricity of each sign; 1 p causes the formation of 2.08 10 9 pairs of ions in 1 cm 3 of air	R	r
	milliroentgen \u003d 10 -3 p	mr	mr
	microroentgen = 10 -6 p	microdistrict	µr
	Rad - the unit of the absorbed dose of any ionizing radiation is equal to rad 100 erg per 1 g of the irradiated medium; when air is ionized by x-rays or γ-rays, 1 p is equal to 0.88 rad, and when tissues are ionized, practically 1 p is equal to 1 rad	glad	rad
	Rem (X-ray biological equivalent) - the amount (dose) of any type of ionizing radiation that causes the same biological effect as 1 p (or 1 rad) of hard X-rays. The unequal biological effect with equal ionization by different types of radiation led to the need to introduce another concept: the relative biological effectiveness of radiation -RBE; the relationship between doses (D) and the dimensionless coefficient (RBE) is expressed as Drem =D rad RBE, where RBE=1 for x-rays, γ-rays and β-rays and RBE=10 for protons up to 10 MeV, fast neutrons and α - natural particles (on the recommendation of the International Congress of Radiologists in Copenhagen, 1953)	reb, reb	rem

Note. Multiple and submultiple units of measurement, with the exception of units of time and angle, are formed by multiplying them by the corresponding power of 10, and their names are attached to the names of units of measurement. It is not allowed to use two prefixes to the name of the unit. For example, you cannot write millimicrowatts (mmkw) or micromicrofarads (mmf), but you must write nanowatts (nw) or picofarads (pf). You should not use prefixes to the names of such units that denote a multiple or submultiple unit of measurement (for example, micron). Multiple units of time may be used to express the duration of processes and designate calendar dates of events.

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Any dimension associated with finding numerical values physical quantities, with the help of them, the patterns of the phenomena that are being studied are determined.

concept physical quantities, For example, forces, weights, etc., is a reflection of the objectively existing characteristics of inertia, extension, and so on, inherent in material objects. These characteristics exist outside and independently of our consciousness, regardless of the person, the quality of the means and methods that are used in the measurements.

Physical quantities that characterize a material object under given conditions are not created by measurements, but are only determined using them. measure any quantity, this means to determine its numerical ratio with some other homogeneous quantity, which is taken as a unit of measurement.

Based on this, measurement is the process of comparing a given value with some of its value, which is taken as unit of measurement.

Relationship formula between the quantity for which the derived unit is established and the quantities A, B, C, ... units they are installed independently, general view:

Where k- numerical coefficient (in the given case k=1).

The formula for relating a derived unit to base or other units is called formuladimensions, and the exponents dimensions For convenience in the practical use of units, such concepts as multiples and submultiples have been introduced.

Multiple unit- a unit that is an integer number of times greater than a system or non-system unit. A multiple unit is formed by multiplying the basic or derived unit by the number 10 to the appropriate positive power.

submultiple unit- a unit that is an integer number of times less than a system or non-system unit. The submultiple unit is formed by multiplying the basic or derived unit by the number 10 to the appropriate negative power.

Definition of the term “unit of measure“.

Unification of the unit of measurement engaged in a science called metrology. IN exact translation is the science of measurement.

Looking into the International Dictionary of Metrology, we find out that unit- this is a real scalar quantity, which is defined and accepted by agreement, with which it is easy to compare any other quantity of the same kind and express their ratio using a number.

A unit of measurement can also be considered as a physical quantity. However, there is a very important difference between a physical quantity and a unit of measurement: the unit of measurement has a fixed numerical value accepted by convention. This means that the units of measurement for the same physical quantity may be different.

For example, weight can have the following units: kilogram, gram, pound, pood, centner. The difference between them is clear to everyone.

The numerical value of a physical quantity is represented by the ratio of the measured value to the standard value, which is unit of measure. A number that has a unit of measure named number.

There are basic and derived units.

Basic units set for such physical quantities that are selected as the main ones in a particular system of physical quantities.

Thus, the International System of Units (SI) is based on the International System of Units, in which the main quantities are seven quantities: length, mass, time, electricity, thermodynamic temperature, amount of substance and luminous intensity. So, in SI, the base units are the units of quantities that are indicated above.

Size of base units set by agreement within a specific system of units and fixed either with the help of standards (prototypes), or by fixing the numerical values ​​of fundamental physical constants.

Derived units are determined through the main method of using those relationships between physical quantities that are established in the system of physical quantities.

There are a huge number of different systems of units. They differ both in the systems of quantities on which they are based and in the choice of base units.

Usually, the state, through laws, establishes a certain system of units that is preferred or mandatory for use in the country. In the Russian Federation, the units of quantities of the SI system are the main ones.

Systems of units of measure.

Metric systems.

• ICSS,

Systems of natural units of measurement.

• atomic system of units,
• planck units,
• Geometric system of units,
• Lorentz-Heaviside units.

Traditional systems of measures.

• Russian system of measures,
• English system of measures,
• French system of measures,
• Chinese system of measures,
• Japanese system of measures,
• Already obsolete (ancient Greek, ancient Roman, ancient Egyptian, ancient Babylonian, ancient Hebrew).

Units of measurement grouped by physical quantities.

• Mass units (mass),
• Temperature units (temperature),
• Distance units (distance),
• Area units (area),
• Volume units (volume),
• Units of measurement of information (information),
• Time units (time),
• Pressure units (pressure),
• Heat flux units (heat flux).