Lust CDA3000 - Appendix A Formula Bank; Mathematical Symbols; A.1.1 si Units; A.1 Mathematical Symbols

A-2
Engineering Guide CDA3000
Appendix A Formula bank
A.1 Mathematical
symbols
Appendix
Equality and inequality
~ proportional < less than
≈
about, approximately > greater than
= equal to
≥
greater than or equal to
corresponding to
≤
less than or equal to
≡
identically equal
«
very small against
not identically equal
»
very large against
≠
not equal, unequal
Geometric symbols
||
parallel
≅
congruent
not parallel angle
↑↑
equivalent to parallel distance AB
↑↓
opposite to parallel arc AB
⊥
rectangular to, perpendicular to ~ similar
∆
triangle
Table 7.3 Geometric symbols
Variable
Formula
symbol
Units Formula
(A cross-
sectional area)
Name Abbreviation
Voltage U Volt V U=I•R
Current rating I Ampere A I = U/R
Resistance R Ohm
Ω
R=U/I
Conductivity, elec. G Siemens S, 1/
Ω
G=1/R
Specif. el. resistance
ρ
Ohm/m
Ω
m; Vm/A
ρ
=1/
σ
El. conductivity
σ, χ
Siemens/m S/m; A/Vm
σ
=1/
ρ
Note: For vector values many formula symbols are designated by German letters.
Table 1.1 SI units
=
AB
AB
A.1.1 SI units