Units of measurement used in electrical and electronic engineering. reference Information

Units of measurement used in electrical and electronic engineering

Background

Basic units of measurement in the SI system

Name physical quantity	Unit	designation
Name physical quantity	Unit	Russian	между popular
Length	meter	м	m
Weight	kilogram	kg	kg
Time	second	с	s
Electric current strength	ampere	A	A
Thermodynamic temperature	kelvin	К	K
Amount of substance	mole	mole	mol
The power of light	candela	cd	cd
Flat angle	radian	glad	rad
Solid angle	steradian	Wed	sr

Definitions of basic and additional units in the SI system

Meter is equal to the length of the path traveled by light in vacuum in a time interval of 1/299 seconds.

Kilogram equal to the mass of the international prototype of the kilogram.

Second is equal to 9 192 631 770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom.

Ampere equal to the strength of an unchanging current, which, when passing through two parallel conductors of infinite length and 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^{^-7} N.

Kelvin equals 1/273,16 of the thermodynamic temperature of the triple point of water.

Mole is equal to the amount of substance of a system containing as many structural elements as there are atoms in carbon-12 weighing 0,012 kg.

Candela equal to the intensity of light in a given direction of a source emitting monochromatic radiation with a frequency of 540 * 10^¹²Hz, the energy intensity of which in this direction is 1/683 W / sr.

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

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

Derived units of electrical and magnetic quantities in the SI system

Value name	Unit
	Name	designation
	Name	Russian	between- popular
Electric current density	ampere per square meter	A/m^²	A / m^²
The amount of electricity; electric charge	pendant	Cl	C
Surface density electric charge	pendant per square meter	C/m^²	C / m^²
Electrical voltage; electric potential, difference electrical potentials; EMF	volt	В	^V
Electric field strength	volts per meter	V/m	V / m
Electric capacity	farad	Ф	F
Absolute permittivity; dielectric constant	farad per meter	f/m	F / m
Electrical resistance	ohm	Om	W
Specific electrical resistance	ohm^.meter	Om^.м	W^.m
Electrical conductivity	Siemens	Cm	S
Specific electrical conductivity	siemens per meter	cm/m	S / m
Magnetic flux	weber	wb	Wb
Magnetic induction	tesla	Tl	T
Inductance	Henry	Mr.	H
Absolute magnetic permeability; magnetic constant	henry per meter	H/m	H / m
Energy	joule	J	J
Active power	watt	Tues	W
Full power	volt-ampere	В^.А	V^.A

Multipliers and prefixes in the SI system

Console	Prefix designation		Factor	Multiplier override
Console	Russian	international	Factor	Multiplier override
exa	Э	E	10¹⁸= 1000000000000000000	quintillion
heel	П	P	10¹⁵= 1000000000000000	quadrillion
tera	Т	T	10¹²= 1000000000000	trillion
gigabyte	Г	G	10⁹= 1000000000	billion
mega	М	M	10⁶= 1000000	million
kilo	к	k	10³= 1000	one thousand
hecto	г	h	10²= 100	one hundred
deck	Yes	da	10¹= 10	ten
-	-	-	10⁰=1	unit
deci	д	d	10^-1= 0,1	one tenth
santi	с	c	10^-2= 0,01	one hundredth
Milli	м	m	10^-3= 0,001	one thousandth
micro	u	m	10^-6= 0,000001	one millionth
nano	н	n	10^-9= 0,000000001	one billionth
picot	п	p	10^-12= 0,000000000001	one trillionth
femto	ф	f	10^-15= 0,000000000000001	one quadrillion
atto	а	a	10^-18= 0,000000000000000001	one quintillionth

Example: 1 µW=0.000001 W=1000 nW

The origin of the names of the SI prefixes.

The first prefixes were introduced in 1793-1795. with the legalization of the metric system of measures in France. It was customary for multiple units of the name of the prefixes to take from the Greek language, for the flat ones - from Latin. In those years, the following prefixes were adopted: kilo... (from the Greek chilioi - a thousand), hecto... (from Greek hekaton - one hundred), deck... (from Greek deka - ten), deci... (from lat. decem - ten), santi... (from lat. centum - one hundred), Milli... (from lat. mille - a thousand).

In subsequent years, the number of multiples and submultiples increased; the names of prefixes for their designation were sometimes borrowed from other languages. The following extensions have appeared: mega... (from Greek megas - big), gigabyte... (from Greek gigas, gigantos - giant), tera... (from Greek teras, teratos - huge, monster), micro... (from Greek mikros - small, small), nano... (from Greek nanos - dwarf), picot... (from Italian piccolo - small, small), femto... (from Danish femten - fifteen), atto... (from Danish atten - eighteen).

The last two prefixes heeland ... exa... - were adopted in 1975: "heel"... (from the Greek. peta - five, which corresponds to five digits of 103), "exa"... (from the Greek hex - six, which corresponds to six digits of 10³).

Publication: radioman.ru

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