IEC 80000-6:2022
(Main)Quantities and units - Part 6: Electromagnetism
Quantities and units - Part 6: Electromagnetism
IEC 80000-6:2022 gives names, symbols, and definitions for quantities and units of electromagnetism. Where appropriate, conversion factors are also given. International Standard IEC 80000-6 has been prepared by IEC technical committee 25: Quantities and units, and their letter symbols in close cooperation with ISO/TC 12, Quantities and units.
This standard is based on classical electromagnetism, i.e. mainly Maxwell’s equations. No reference is made to quantum field theories.
IEC 80000-6:2022 cancels and replaces the first edition published in 2008. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
1) With the new definitions in SI, some previously exact values for quantities now must be determined experimentally while other quantities are given as exact values;
2) Item 6-2.2, elementary charge added;
3) Item 6-11.4, induced voltage, added;
4) Index of entries added;
5) Editorial alignment to other parts of the IEC and ISO 80000 series.
Grandeurs et unités - Partie 6: Electromagnétisme
L'IEC 80000-6:2022 donne des noms, des symboles et des définitions pour les grandeurs et les unités d'électromagnétisme. Le cas échéant, des facteurs de conversion sont également indiqués.
Cette norme est basée sur l'électromagnétisme classique, c'est-à-dire principalement les équations de Maxwell. Aucune référence n'est faite aux théories quantiques des champs.
L’IEC 80000-6 a été établie par le comité d'études 25 de l’IEC: Grandeurs et unités, et leurs symboles littéraux, en coopération étroite avec l'ISO/TC 12, Grandeurs et unités. Il s'agit d'une Norme internationale.
Cette deuxième édition de l’IEC 80000-6 annule et remplace la première édition parue en 2008. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
1) avec les nouvelles définitions du SI, certaines valeurs auparavant exactes pour des grandeurs doivent maintenant être déterminées de manière expérimentale, tandis que d'autres grandeurs sont données comme des valeurs exactes;
2) ajout de l’article 6-2.2, charge élémentaire;
3) ajout de l’article 6-11.4, tension induite;
4) ajout d’un index des entrées;
5) alignement rédactionnel sur d'autres parties des séries IEC et ISO 80000.
General Information
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Standards Content (Sample)
IEC 80000-6
Edition 2.0 2022-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Quantities and units –
Part 6: Electromagnetism
Grandeurs et unités –
Partie 6: Électromagnétisme
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IEC 80000-6
Edition 2.0 2022-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Quantities and units –
Part 6: Electromagnetism
Grandeurs et unités –
Partie 6: Électromagnétisme
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 01.040.29; 17.220.01 ISBN 978-2-8322-5706-7
– 2 – IEC 80000-6:2022 © IEC 2022
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
0.1 Tables of quantities. 5
0.2 Units . 5
0.2.1 General . 5
0.2.2 Remark on units for quantities of dimension one, or dimensionless
quantities . 5
0.3 Numerical statements in this document . 6
0.4 Special remarks . 6
0.4.1 General . 6
0.4.2 System of quantities . 6
0.4.3 Sinusoidal quantities. 7
0.4.4 Root-mean-square value, RMS value . 7
1 Scope . 8
2 Normative references . 8
3 Names, symbols, definitions and units of quantities . 8
Annex A (informative) Units in the CGS system with special names . 27
Alphabetical index . 28
Bibliography . 34
Table 1 – Quantities and units in electromagnetism . 9
Table A.1 – Deprecated units with special names taken from the CGS system . 27
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
QUANTITIES AND UNITS –
Part 6: Electromagnetism
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 80000-6 has been prepared by IEC technical committee 25: Quantities and units, and their
letter symbols in close cooperation with ISO/TC 12, Quantities and units. It is an International
Standard.
This second edition of IEC 80000-6 cancels and replaces the first edition published in 2008.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) With the new definitions in SI, some previously exact values for quantities now must be
determined experimentally while other quantities are given as exact values;
b) Item 6-2.2, elementary charge added;
c) Item 6-11.4, induced voltage, added;
d) Index of entries added;
e) Editorial alignment to other parts of the IEC and ISO 80000 series.
– 4 – IEC 80000-6:2022 © IEC 2022
The text of this International Standard is based on the following documents:
Draft Report on voting
25/732/FDIS 25/740/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
IEC 80000 consists of the following parts, under the general title Quantities and units:
1) Part 6: Electromagnetism
2) Part 13: Information science and technology
3) Part 15: Logarithmic and related quantities, and their units
4) Part 16: Printing and writing rules
5) Part 17: Time dependency
The following parts are published by ISO:
1) Part 1: General
2) Part 2: Mathematical signs and symbols to be used in the natural sciences and technology
3) Part 3: Space and time
4) Part 4: Mechanics
5) Part 5: Thermodynamics
6) Part 7: Light
7) Part 8: Acoustics
8) Part 9: Physical chemistry and molecular physics
9) Part 10: Atomic and nuclear physics
10) Part 11: Characteristic numbers
11) Part 12: Condensed matter physics
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
0.1 Tables of quantities
The names in English of the most important quantities within the field of this document are given
together with their symbols and, in most cases, their definitions. The definitions are given for
identification of the quantities in the International System of Quantities (ISQ), listed in Table 1;
they are not intended to be complete.
The scalar, vectorial or tensorial character of quantities is pointed out, especially when this is
needed for the definitions.
In most cases, only one name and only one symbol for the quantity are given; where two or
more names or two or more symbols are given for one quantity and no special distinction is
made, they are on an equal footing. When two types of italic letters exist (for example as with
ϑ and θ; φ and φ; a and a; g and g) only one of these is given. This does not mean that the other
is not equally acceptable. It is recommended that such variants should not be given different
meanings. A symbol within parenthesis implies that it is an alternative symbol, to be used when,
in a particular context, the main symbol is in use with a different meaning.
0.2 Units
0.2.1 General
The names of units for the corresponding quantities are given together with the international
symbols and the definitions. These unit names are language-dependent, but the symbols are
th
international and the same in all languages. For further information, see the SI Brochure (9
edition 2019) from BIPM and ISO 80000-1.
The units are arranged in the following way:
a) The base SI units are given first. The SI units have been adopted by the General Conference
on Weights and Measures (Conférence Générale des Poids et Mesures, CGPM). The use
of base SI units, and their decimal multiples and submultiples formed with the SI prefixes
are recommended, although the decimal multiples and submultiples are not explicitly
mentioned. The order of the units is kg, m, s, A, K, mol, cd.
b) Some non-SI units are then given, being those accepted by the International Committee for
Weights and Measures (Comité International des Poids et Mesures, CIPM), or by the
International Organization of Legal Metrology (Organisation Internationale de Métrologie
Légale, OIML), or by ISO and IEC, for use with the SI.
c) Non-SI units that are not recommended are given only in annexes in some parts of
ISO 80000 and IEC 80000. These annexes are informative, in the first place for the
conversion factors, and are not integral parts of the standard. These deprecated units are
arranged in two groups:
1) units in the CGS system with special names, see Annex A;
2) units based on the foot, pound, and some other related units.
0.2.2 Remark on units for quantities of dimension one, or dimensionless quantities
The coherent unit for any quantity of dimension one, also called a dimensionless quantity, is
the number one, symbol 1. When the value of such a quantity is expressed, the unit symbol 1
is generally not written out explicitly.
EXAMPLE
Refractive index n = 1,53 × 1 = 1,53
– 6 – IEC 80000-6:2022 © IEC 2022
Prefixes shall not be used to form multiples or submultiples of this unit. Instead of prefixes,
powers of 10 are recommended.
EXAMPLE
Reynolds number Re = 1,32 × 10
Considering that plane angle is generally expressed as the ratio of two lengths and solid angle
as the ratio of two areas, in 1995 the CGPM specified that, in the SI, the radian, symbol rad,
and steradian, symbol sr, are dimensionless derived units. This implies that the quantities plane
angle and solid angle are considered as derived quantities of dimension one. The units radian
and steradian are thus equal to one; they may either be omitted, or they may be used in
expressions for derived units to facilitate distinction between quantities of different kinds, but
having the same dimension.
0.3 Numerical statements in this document
The sign = is used to denote "is exactly equal to" and the sign ≈ is used to denote "is
approximately equal to".
Numerical values of physical quantities that have been experimentally determined always have
an associated measurement uncertainty. This uncertainty should always be specified. In this
document, the magnitude of the uncertainty is represented as in the following example.
EXAMPLE
l = 2,347 82(32) m
In this example, l = a(b) m, the numerical value of the uncertainty b indicated in parentheses is
assumed to apply to the last (and least significant) digits of the numerical value a of the length
l. This notation is used when b represents one standard uncertainty (estimated standard
deviation) in the last digits of a. The numerical example given above can be interpreted to mean
that the best estimate of the numerical value of the length l, when l is expressed in the unit
metre, is 2,347 82 and that the unknown value of l is believed to lie between
(2,347 82 −0,000 32) m and (2,347 82 +0,000 32) m with a probability determined by the
standard uncertainty 0,000 32 m and the probability distribution of the values of l.
0.4 Special remarks
0.4.1 General
The items given in IEC 80000-6 are generally in conformity with the International
Electrotechnical Vocabulary (IEV), especially IEC 60050-121 and IEC 60050-131. For each
quantity, the reference to IEV is given in the form: "See IEC 60050-121:20XX, 121-xx-xxx.".
The font used for text is sans serif; that used for quantities is serif.
0.4.2 System of quantities
For electromagnetism, several different systems of quantities have been developed and used
depending on the number and the choice of base quantities on which the system is based.
However, in electromagnetism and electrical engineering, only the International System of
Quantities, ISQ, and the associated International System of Units, SI, are acknowledged and
are reflected in the standards of ISO and IEC. The SI has seven base units, among them are
the kilogram (kg), the metre (m), the second (s), and the ampere (A).
0.4.3 Sinusoidal quantities
For quantities that vary sinusoidally with time, and for their complex representations, the IEC
has standardized two ways to build symbols. Capital and lowercase letters are generally used
for electric current (item 6-1) and for voltage (item 6-11.3), and additional symbols for other
quantities. These are given in IEC 60027-1.
EXAMPLE 1
The sinusoidal variation with time of an electric current (item 6-1) can be expressed in real
representation as
i = 2 I cos ωt – φ
( )
and its complex representation (termed phasor) is expressed as
−jφ
i = I e
where i is the instantaneous value of the current, I, is its root-mean-square (RMS) value
(see 0.4.4), (ωt − φ) is the phase, φ is the initial phase, and j is the imaginary unit (j = −1), in
mathematics often denoted by i.
EXAMPLE 2
The sinusoidal variation with time of a magnetic flux (item 6-22.1) can be expressed in real
representation as
Φ Φ cos ωt – φφ 2 Φ cos ωt –
( ) ( )
eff
where Φ is the instantaneous value of the flux, is its peak value and Φ is its RMS value.
Φ
eff
0.4.4 Root-mean-square value, RMS value
For a time-depending quantity a, the positive square root of the mean value of the square of the
quantity taken over a given time interval is called root-mean-square value, i.e.
T
atd
∫
T
The root-mean-square value of a periodic quantity is usually taken over an integration interval,
the range of which is the period multiplied by a natural number. For a sinusoidal quantity
a(t) = Â cos(ωt + φ), the root-mean-square value is Â/ 2 .
The root-mean-square value of a quantity may be denoted by adding one of the subscripts "eff"
or "RMS" to the symbol of the quantity. In electrical technology, the root-mean-square values
of electric current i(t) and voltage u(t) are usually denoted I and U, respectively.
==
– 8 – IEC 80000-6:2022 © IEC 2022
QUANTITIES AND UNITS –
Part 6: Electromagnetism
1 Scope
This part of IEC 80000 gives names, symbols, and definitions for quantities and units of
electromagnetism. Where appropriate, conversion factors are also given.
This document is based on classical electromagnetism, i.e. mainly Maxwell’s equations. No
reference is made to quantum field theories.
2 Normative references
There are no normative references in this document.
3 Names, symbols, definitions and units of quantities
The names, symbols, and definitions for quantities and units of electromagnetism are given in
the tables on the following pages. For units in the CGS system with special names, see Annex A.
NOTE 1 In general, these quantities can depend on time even when not explicitly noted. All surfaces are assumed
to be oriented surfaces (see IEC 60050-102, item 102-04-37)
NOTE 2 The font in the formulas is different from the font of the main text.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
Table 1 – Quantities and units in electromagnetism
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-1 electric current I scalar quantity equal to the quotient of the net A Electric current is one of the base
quasi-infinitesimal (see IEC 60050-121, item quantities in the International System of
i
121-11-06) electric charge dQ (item 6-2.1) Quantities, ISQ, on which the
transferred through a surface during a quasi- International System of Units, SI, is
infinitesimal time interval and the duration dt of based.
that interval:
Electric current I through a surface S
can also be written as
dQ
I =
dt
IA J⋅ e d
∫ n
S
where J is the electric current density
(item 6-8) and where e dA is the vector
n
surface element.
Electric current produces a magnetic
field.
For related definitions, see item 6-8 and
IEC 60050-121:1998, 121-11-13.
6-2.1 electric charge Q additive scalar quantity attributed to any particle C To denote a point charge, q is often
and, generally, any system of them, to used, as is done in this document.
q A s
characterize its electromagnetic interactions
Electromagnetic interactions are
s A
Coulomb-Lorentz forces, see
IEC 60050 121:1998, 121-11-20.
The coherent SI unit of charge is
coulomb, C. Another frequently used unit
is the ampere-hour (Ah) mentioned in
IEC 60050-313:2020, 313-01-16, widely
used for battery characteristics.
=
– 10 – IEC 80000-6:2022 © IEC 2022
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-2.2 elementary charge e magnitude of the negative electric charge carried C In the SI system the elementary charge,
by a single electron, which has charge −1 e e, is one of the fundamental constants
A s
with an exact value
s A
−19
e = 1,602 176 634 × 10 C, see the SI
Brochure.
Electric charge can be positive, negative
or zero. The sign convention is such that
the elementary electric charge, e, of the
proton, is positive. See IEC 60050-113,
item 113-02-12.
6-3 electric charge density, scalar quantity representing the spatial distribution See IEC 60050-121:1998, 121-11-07.
ρ C/m
volumic electric charge of electric charge,
−3
m s A
volumic charge
dQ
ρ r =
( )
dV
where dQ is quasi-infinitesimal (see
IEC 60050-121:2008, 121-11-06) electric charge
(item 6-2.1) contained in a quasi-infinitesimal 3D
domain located at position r and dV is quasi-
infinitesimal volume (ISO 80000-3) of this domain
6-4 surface density of electric charge, scalar quantity representing the areal distribution See IEC 60050-121:1998, 121-11-08.
σ C/m
areic electric charge of electric charge,
−2
m s A
areic charge
dQ
σσ r
( )
dA
where dQ is a quasi-infinitesimal (see
IEC 60050-121:2008, 121-11-06) electric charge
(item 6-2.1) contained in a quasi-infinitesimal 2D
domain located at position r, and dA is a quasi-
infinitesimal area (ISO 80000-3) of this domain
==
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-5 linear density of electric charge, scalar quantity representing the linear distribution C/m See IEC 60050-121, item 121-11-09.
τ
lineic electric charge of electric charge,
−1
m s A
lineic charge
dQ
τ τ (r )
dl
where dQ is a quasi-infinitesimal (see
IEC 60050-121:2008, 121-11-06) electric charge
(item 6-2.1) contained in a quasi-infinitesimal
domain located at position r and dl is a quasi-
infinitesimal length (ISO 80000-3) of this domain
6-6 electric dipole moment p vector quantity given by C m The electric dipole moment of a
substance within a domain is the vector
p = q(r – r ) m s A
+ – sum of electric dipole moments of all
electric dipoles contained in the domain.
where r and r are the position vectors
+ –
See IEC 60050-121:1998, 121-11-35
(ISO 80000-3) of the carriers of electric charges q
and 121-11-36.
and −q (item 6-2), respectively
6-7 electric polarization P vector quantity representing the spatial distribution See IEC 60050-121:1998, 121-11-37.
C/m
of electric dipole moment,
−2
m s A
dp
Pr( ) =
dV
where dp is quasi-infinitesimal (see
IEC 60050-121:2008, 121-11-06) electric dipole
moment (item 6-6) of a substance in a quasi-
infinitesimal domain at position r and dV is quasi-
infinitesimal volume (ISO 80000-3) of this domain
6-8 electric current density J vector quantity equal to the sum, for the charge There can be different charge carriers
A/m
carriers within a volume element of quasi- with different velocities.
−2
m A
infinitesimal volume V, of the products of their
Electric current I (item 6-1) through a
electric charge Q and their velocity v , divided by
i i
surface S is
the volume V, given by
I = J e dA
Jr( ) J ρv n
∫
S
where i is the rank of the charge carrier
where e dA is the vector surface
n
element.
See IEC 60050-121:1998, 121-11-11.
= =
==
– 12 – IEC 80000-6:2022 © IEC 2022
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-9 linear electric current density J vector quantity equal to the sum, for the charge A/m See IEC 60050-121:1998, 121-11-12.
S
carriers confined to a surface element of quasi-
−1
m A
infinitesimal area S, of the products of their electric
charge Q and their velocity v , divided by the area
i i
S
J r J σv
( )
SS
where i is the rank of the charge carrier
6-10 electric field strength E additive vector field quantity that exerts on any V/m See IEC 60050-121:1998, 121-11-18.
charged particle located at position r a force F
−3 −1
kg m s A
(ISO 80000-4) equal to the product of E and
electric charge q (item 6-2.1) of the particle, thus:
F
Er( ) =
q
6-11.1 electric potential V scalar quantity expressed by V The electric potential is not unique since
any constant scalar field quantity can be
2 −3 −1
φ
kg m s A
added to it without changing its gradient.
∂A
–grad V = E +
The electric potential, the electric field,
∂t
and the magnetic vector potential
where E is electric field strength (item 6-10), A is
depend on the position.
magnetic vector potential (item 6-32) and t is time
See IEC 60050-121:1998, 121-11-25.
(ISO 80000-3)
6-11.2 electric potential difference V scalar quantity given by V r
b
ab
∂A
V Er+⋅ d
∫
2 −3 −1 ab
V = V − V
kg m s A
∂t
ab a b
r
a (C)
where V and V are the electric potentials (item
a b
where E is electric field strength (item 6-
6-11.1) at points a and b, respectively
10), A is magnetic vector potential (item
6-32), t is time (ISO 80000-3), and r is
the position vector (ISO 80000-3) along
a given curve C, from point a to point b.
See IEC 60050-121, item 121-11-26.
=
= =
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-11.3 voltage, U for a conductor, scalar quantity given by the V The name "voltage", commonly used in
electric tension electric potential difference V (6-11.2) between the English language, is given in the
ab
2 −3 −1
U
kg m s A
ab, IEV, but it is an exception to the
two points a and b respectively
principle that a quantity name should not
u
refer to any name of a unit.
See IEC 60050-121:2002, 121-11-27.
6-11.4 induced voltage U negative of time derivative of protoflux (item V If the integration path is closed, the loop
i
6-22.2) voltage is
2 −3 −1
kg m s A
d ddΦ
U – A⋅ dr U =− A⋅=dr −
i ∫ l
∫
C
C
dt ddt t
6-12 electric flux density, D vector quantity given by The electric flux density is related to
C/m
electric displacement
electric charge density via div D = ρ
−2
D = ε E + P
m s A
0 where div denotes divergence.
is electric constant (item 6-14.1), E is
where ε The electric flux density, the electric
field strength, and the polarization
electric field strength (item 6-10), and P is electric
depend on the position.
polarization (item 6-7)
See IEC 60050-121:1998, 121-11-40.
6-13 capacitance C for a capacitive element, quotient of electric F The electric charge of a capacitive
charge Q and voltage U (item 6-11.3); element is given by the time integral of
−1 −2 4 2
kg m s A
the electric current.
Q
C =
See IEC 60050-131:2008, 131-12-11.
U
6-14.1 electric constant, ε scalar quantity given by F/m See IEC 60050-121:2021, 121-11-03.
permittivity of vacuum
−1 −3 4 2
This quantity is considered to be
kg m s A
ε = constant in time.
μc
where µ is the magnetic constant (item 6-26.1)
and c is luminal speed (item 6-35.2)
=
– 14 – IEC 80000-6:2022 © IEC 2022
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-14.2 permittivity ε for linear media, proportionality constant between F/m Permittivity ε is a property of a medium.
electric flux density D (item 6-12) and electric field For an inhomogeneous medium,
‒1 ‒3 4 2
kg m s A
strength E (item 6-10); permittivity ε depends on position.
D = εE For an isotropic medium, ε is a scalar
quantity; for an anisotropic medium, ε is
a second-order tensor.
See IEC 60050-121:2021, 121-12-12.
6-15 relative permittivity ε 1 See IEC 60050-121:2021, 121-12-13.
for linear media, quotient of permittivity ε (item 6-
r
14.2) and the electric constant ε (item 6-14.1);
ε
ε =
r
ε
6-16 electric susceptibility χ for linear media, scalar quantity expressed by 1 χ = ε − 1 where ε is relative permittivity
r r
(item 6-15)
P = ε χ E
Electric susceptibility χ is a property of a
where P is electric polarization (item 6-7), ε is the
medium. For an inhomogeneous
electric constant (item 6-14.1), and E is electric
medium, electric susceptibility χ
field strength (item 6-10)
depends on position.
For an isotropic medium, χ is a scalar
quantity; for an anisotropic medium, χ is
a second order tensor.
See IEC 60050-121:1998, 121-12-19.
6-17 electric flux Ψ scalar quantity given by the integral C See IEC 60050-121:1998, 121-11-41.
s A
ΨA= D ⋅ e d
∫ n
S
over a surface S, where D is electric flux density
(item 6-12) and e dA is a vector surface element
n
(ISO 80000-3)
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-18 displacement current density J vector quantity given by See IEC 60050-121:1998, 121-11-42.
A/m
D
−2
m A
∂D
J =
D
∂t
where D is electric flux density (item 6-12) and t is
time (ISO 80000-3)
I
6-19.1 displacement current scalar quantity given by the integral A See IEC 60050-121:1998, 121-11-43.
D
IA Je⋅d
D ∫ Dn
S
over a surface S, where J is displacement current
D
density (item 6-18) and e dA is a vector surface
n
element (ISO 80000-3)
6-19.2 total current I , I scalar quantity given by the sum of electric current A See IEC 60050-121:1998, 121-11-45.
tot t
I (item 6-1) and displacement current I (item
D
6-19.1);
I = I + I
tot D
6-20 total current density J , J vector quantity given by the sum of electric current See IEC 60050-121:1998, 121-11-44.
A/m
tot t
density J (item 6-8) and displacement current
−2
m A
density J (item 6-18);
D
J = J + J
tot D
6-21 magnetic flux density B vector quantity expressed by T The magnetic flux density depends on
position.
−2 −1
F = qv × B
kg s A
See IEC 60050-121:1998, 121-11-19.
where F is the force (ISO 80000-4) acting on a test
particle with electric charge q (item 6-2) traversing
a magnetic field with flux density B, with velocity v
(ISO 80000-3)
=
– 16 – IEC 80000-6:2022 © IEC 2022
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-22.1 magnetic flux Φ scalar quantity given by the integral Wb Magnetic flux can also be given by the
line integral of the magnetic vector
2 −2 −1
kg m s A
potential A, (item 6-32) over a closed
ΦA Be⋅d
∫ n
S
curve C which is the border of area S:
over a surface S, where B is magnetic flux density
Φ = Ar d
∫
(item 6-21) and e dA is a vector surface element C
n
(ISO 80000-3)
See IEC 60050-121:1998, 121-11-21.
6-22.2 protoflux Ψ scalar quantity given by the integral Wb The former name "linked flux" is
p
deprecated.
2 −2 −1
kg m s A
Ψ Ar⋅d
p ∫
See IEC 60050-121:2021, 121-11-24.
C
where A is magnetic vector potential (item 6-32)
and dr is a line vector element of the path C
6-22.3 linked magnetic flux Φ magnetic flux (6-22.1), the integration surface of Wb See IEC 60050-121:2021, 121-11-24.
l
which is such that magnetic field lines cross it in
2 −2 −1
kg m s A
the same orientation more than once
6-22.4 total magnetic flux Ψ highest value of the magnetic flux (6-22.1) Wb The integration surface for the magnetic
produced by a current loop flux has to be chosen such that it is
2 ‒2 ‒1
Φ
kg m s A
m crossed in the same direction by all
magnetic field lines produced by the
current loop.
The total flux can be a linked flux
(6-22.3).
=
=
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-23 magnetic moment, m additive vector quantity, for a quasi-infinitesimal A magnetic moment is associated with
A m
magnetic area moment (see IEC 60050-121:2008, 121-11-06) planar loop systems of charged particles, such as
m A
given by atoms, molecules, atomic nuclei,
nucleons. It can be considered as a
m = I e A
n product of the motion of charged
particles and the magnetic moments of
where I is the electric current (item 6-1) in a loop,
these particles.
e is a unit vector perpendicular to the planar
n
Magnetic moment is also an intrinsic
surface S enclosed by the loop, and A is the area
property of any charged elementary
(ISO 80000-3) in the loop
particle with half-integer spin (e.g. an
electron, a neutron or a quark).
The magnetic moment of a substance
within a domain is the vector sum of the
magnetic moments of all entities
contained in the domain.
See IEC 60050-121:1998, 121-11-49
and 121-11-50.
6-24 magnetization M, H vector quantity representing the spatial distribution A/m See IEC 60050-121:1998, 121-11-52.
i
of the magnetic moment,
−1
m A
dm
Mr( ) =
dV
where dm is quasi-infinitesimal (see
IEC 60050-121:2008, 121-11-06) magnetic
moment (item 6-23) of a substance contained in a
3D domain located at position r, and dV is volume
(ISO 80000-3) of this domain
6-25 magnetic field strength, H vector quantity given by A/m The magnetic field strength is related to
magnetizing field the total current density J (item 6-20)
tot
−1
m A
B
via
H − M
μ
rot H = J
tot
where B is magnetic flux density (item 6-21), μ is
The magnetic field strength, the
the magnetic constant (item 6-26.1), and M is the
magnetic flux density, and the
magnetization (item 6-24)
magnetization depend on the position.
See IEC 60050-121:1998, 121-11-56.
=
– 18 – IEC 80000-6:2022 © IEC 2022
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-26.1 magnetic constant, μ scalar quantity given by H/m This quantity is considered to be
permeability of vacuum constant in time.
−7 −2 −2
μ ≈ 4π × 10 H/m with a relative standard kg m s A
The numerical value of the magnetic
−10
uncertainty of 2,3 × 10
constant was originally exactly
−7
4π × 10 . It must be determined
experimentally; see the SI Brochure.
See the SI Brochure and IEC 60050-
121:2021, 121-11-14.
6-26.2 permeability μ for linear media, proportionality constant between H/m Permeability µ is a property of a
magnetic flux density B (item 6-21) and magnetic medium. For an inhomogeneous
−2 −2
kg m s A
field strength H (item 6-25) medium, permeability µ depends on
position. For an isotropic medium, µ is a
B = μH
scalar quantity; for an anisotropic
medium, µ is a second order tensor.
See IEC 60050-121:2021, 121-12-28.
6-27 relative permeability μ for linear media, quotient of permeability μ (item 6- 1 See IEC 60050-121:2021, 121-12-29.
r
26.2) and the magnetic constant μ (item 6-26.1)
μ
μ =
r
μ
6-28 magnetic susceptibility for linear media, proportionality constant between 1 κ = µ – 1 where μ is relative
κ, χ
r r
m
magnetization M (item 6-24) and magnetic field
permeability (item 6-27).
strength H (item 6-25)
This definition applies to an isotropic
M = κ H
medium. For an anisotropic medium,
magnetic susceptibility is a second order
tensor.
The magnetization and the magnetic
field strength depend on position.
See IEC 60050-121:1998, 121-12-37.
6-29 magnetic polarization J vector quantity given by the product of the T See IEC 60050-121:1998, 121-11-54.
m
magnetic constant μ (item 6-26.1) and
Wb/m
magnetization M (item 6-24)
−2 −1
kg s A
J = μ M
m 0
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-30 magnetic dipole moment j , j vector quantity given by the product of the Wb m See IEC 60050-121:1998, 121-11-55.
m
magnetic constant μ (item 6-26.1) and magnetic
3 −2 −1
kg m s A
moment m (item 6-23)
j = μ m
m 0
6-31 coercivity, H scalar quantity giving the magnetic field strength A/m See IEC 60050-121:1998, 121-12-69.
c
coercive field strength (item 6-25) to be applied to bring the magnetic flux
−1
m A
density (item 6-21) in a substance from its
remanent magnetic flux density to zero
6-32 magnetic vector potential A vector quantity expressed by J/(A m) The magnetic vector potential is not
unique since any irrotational vector field
−2 −1
B = rot A
kg m s A
can be added to it without changing its
rotation.
where B is magnetic flux density (item 6-21)
The magnetic vector potential and the
magnetic flux density depend on
position.
See IEC 60050-121:1998, 121-11-23.
6-33 electromagnetic energy density w scalar quantity given by the sum of scalar Electromagnetic energy is a special kind
J/m
products: of energy (ISO 80000-5). The
−1 −2
kg m s
electromagnetic energy density depends
w = (1/2)(E ⋅ D + B ⋅ H)
on position.
where E is electric field strength (item 6-10), D is
See IEC 60050-121:1998, 121-11-65.
electric flux density (item 6-12), B is magnetic flux
density (item 6-21), and H is magnetic field
strength (item 6-25)
6-34 Poynting vector S vector quantity given by the vector product The Poynting vector depends on the
W/m
position.
−3
S = E × H
kg s
See IEC 60050-121:2019, 121-11-66.
where E is electric field strength (item 6-10) and H
is magnetic field strength (item 6-25)
6-35.1 phase speed of electromagnetic c scalar quantity given by the quotient of angular m/s See ISO 80000-3.
waves frequency ω (ISO 80000-3) and angular
−1
m s
wavenumber k (ISO 80000-3) in a given direction:
ω
c =
k
– 20 – IEC 80000-6:2022 © IEC 2022
Quantity Unit
Item No. Remarks
Name Symbol Definition Symbol
6-35.2 speed of light in vacuum, c scalar quantity equal to the speed of m/s This value is not only valid for
light speed in vacuum, electromagnetic waves in vacuum (ISO 80000-1) electromagnetic waves in vacuum, but
−1
m s
luminal speed also for gravitational waves. It is also the
c = 299 792 458 m/s
0 upper limit for the speed of propagation
of information since this requires a
physical carrier. This quantity is
considered to be constant in time.
Its value has been fixed by CGMP (see
the SI Brochure).
See also IEC 60050-113:2020,
113-01-34.
6-36 source voltage, U voltage (item 6-11.3) between the two terminals of V The name "electromotive force" with the
s
source tension an electric source when there is no electric current abbreviated term EMF, and the symbol E
2 −3 −1
kg m s A
(item 6-1) through the source are deprecated.
See IEC 60050-131:2013, 131-12-22.
for an irrotational magnetic field strength, scalar The magnetic scalar potential is not
6-37.1 magnetic potential V , φ A
m
quantity expressed by unique since any constant scalar field
can be added to it without changing its
H = –grad V
m gradient.
where H is magnetic field strength (item 6-25) See IEC 60050-121:1998, 121-11-58.
6-37.2 magnetic tension U in a magnetic field strength, scalar quantity given A For an irrotational magnetic field
m
by the line integral along a given curve C from strength, this quantity is equal to the
point a to point b; magnetic potential difference.
See IEC 60050-121:1998, 121-11-57.
r
b
U Hr⋅ d
m
∫
r C
( )
a
where H is magnetic field strength (item 6-25) and
r is position vector (ISO 80000-3)
F
6-37.3 magnetomotive force scalar quantity given by the line integral along a A Compare to the remark in item 6-36.
m
closed curve C;
See IEC 60050-121:1998, 121-11-60.
F H⋅ dr
m ∫
C
where H is magnetic field strength (item 6-25) and
r is position vector (ISO 80000-3)
6-38 number of turns in a winding N
...
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