ISO 31-5 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to electricity and magnetism. It is superseded by ISO 80000-6.
Some of its definitions are below, with values taken from NIST values of the constants:
Name | Symbol | Definition | Value |
---|---|---|---|
Speed of light in vacuum | c0 | 299 792 458 m s−1 | 299 792 458 m s−1 |
Magnetic constant | 4 |
12.566 370 614... x 10−7 N A−2 | |
Electric constant | 8.854 187 817... x 10−12 F m−1 | ||
Characteristic impedance of vacuum | Z0 | 376.730 313 461... |