ISO 31-5
From Wikipedia, the free encyclopedia
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.
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 | μ0 | 4π × 10−7 N A−2 | 12.566 370 614... x 10−7 N A−2 |
| Electric constant | ε0 |  |
8.854 187 817... x 10−12 F m−1 |
| Characteristic impedance of vacuum | Z0 | μ0 c0 | 376.730 313 461...Ω |
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