- Electromagnetics I
- Ch 1: Preliminary Concepts
- Loc 1.7
- Electromagnetics I
- Ch 1
- Loc 1.7
Notation
The list below describes notation used in this book.
- Vectors: Boldface is used to indicate a vector; e.g., the electric field intensity vector will typically appear as
. Quantities not in boldface are scalars. When writing by hand, it is common to write “
” or “
” in lieu of “
.”
- Unit vectors: A circumflex is used to indicate a unit vector; i.e., a vector having magnitude equal to one. For example, the unit vector pointing in the
direction will be indicated as
. In discussion, the quantity “
” is typically spoken “x hat.”
- Time: The symbol
is used to indicate time.
- Position: The symbols
,
and
indicate positions using the Cartesian, cylindrical, and polar coordinate systems, respectively. It is sometimes convenient to express position in a manner which is independent of a coordinate system; in this case, we typically use the symbol
. For example,
in the Cartesian coordinate system.
- Phasors: A tilde is used to indicate a phasor quantity; e.g., a voltage phasor might be indicated as
, and the phasor representation of
will be indicated as
.
- Curves, surfaces, and volumes: These geometrical entities will usually be indicated in script; e.g., an open surface might be indicated as
and the curve bounding this surface might be indicated as
. Similarly, the volume enclosed by a closed surface
may be indicated as
.
- Integrations over curves, surfaces, and volumes will usually be indicated using a single integral sign with the appropriate subscript. For example:
is an integral over the curve
is an integral over the surface
is an integral over the volume
.
- Integrations over closed curves and surfaces will be indicated using a circle superimposed on the integral sign. For example:
is an integral over the closed curve
is an integral over the closed surface
A “closed curve” is one which forms an unbroken loop; e.g., a circle. A “closed surface” is one which encloses a volume with no openings; e.g., a sphere.
- The symbol “
” means “approximately equal to.” This symbol is used when equality exists, but is not being expressed with exact numerical precision. For example, the ratio of the circumference of a circle to its diameter is
, where
.
- The symbol “
” also indicates “approximately equal to,” but in this case the two quantities are unequal even if expressed with exact numerical precision. For example,
as a infinite series, but
for
. Using this approximation
, which is in good agreement with the actual value
.
- The symbol “
” indicates “on the order of,” which is a relatively weak statement of equality indicating that the indicated quantity is within a factor of 10 or so the indicated value. For example,
for a class of iron alloys, with exact values being being larger or smaller by a factor of 5 or so.
- The symbol “
” means “is defined as” or “is equal as the result of a definition.”
- Complex numbers:
.
- See Appendix C for notation used to identify commonly-used physical constants.
Ellingson, Steven W. (2018) Electromagnetics, Vol. 1. Blacksburg, VA: VT Publishing. https://doi.org/10.21061/electromagnetics-vol-1 CC BY-SA 4.0
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