mho
Electrical conductanceexact by definition
The mho is the siemens under its older name, exactly equal to it. One mho is one ampere per volt, so a one ohm resistor has a conductance of one mho. The equality is exact by definition, this being a renaming rather than a conversion.
Watch out: The upside-down omega glyph has no font metrics in this site's renderer, so the symbol here is spelled out as mho. On paper it is written ℧.
| 1 mho | 1 S |
Ohm spelled backwards, proposed by William Thomson in the 1880s and given the symbol of an upside-down omega. The CGPM adopted the siemens in 1971 and the mho has been deprecated since, but it is still printed on older meters and in American textbooks of that era, and transconductance in valve and transistor data is often given in micromhos.