The ampere is defined as: "that constant current which, if maintained in
two straight parallel conductors of infinite length, of negligible circular
cross-section, and placed one metre apart in vacuum, would produce between
these conductors a force equal to 2?10?7 newtons per metre of length".
Noticed that there is no specification as to the signum. Both flowing
positive charges and flowing negative charges would have a magnitude of 1 A
if the conditions otherwise held.
Now, you might be thinking that it is clearly the positive current because
the opposite current would be -1 A. This is kinda true (and kinda untrue),
but it does not alleviate the problem anyway. See, we still do not know
which particles have positive electric charge under this definition and
which have negative - the definition has a degree of freedom.
In English, protons have been defined to have positive charge. This is
unfortunate for many reasons. The most obvious and relevant of these
reasons is the fact that it is rare for protons to flow - but not rare for
electrons to do so. If we are defining the ampere, then we can choose are
sign convention as we wish, and it would make sense to define it in terms
of those things which do actually flow in normal life.
Therefore, I propose that this definition in Lojban carry with it a
negative sign relative to English convention, by default. The flow of
electrons (or conventional charges) will be measured in terms of positive
xampo; the flow of protons will be measured in terms of negative xampo. If
necessary, this standard/convention can be specified in x3, but it should
be the default setting.
Note that this would align with my definition of ".eldicka'u" and of
"ku'arkydicka'u". This makes sense because a certain (integer) number of
these elementary charges make up what the coulomb should be (although its
current definition does not admit of this possibility with certainty). If
the elementary charges, in our convention, are negative relative to English
convention (wherein the proton has positive charge), then so should the
Lojban should make efforts to perfect the imperfections of natural
languages and historical accidents within them. This would be one such
We are free to define our base SI-derived words as we wish. We already do
so, by assigning the gram ("grake") as the gismu rather than the
kilogram. This would be another such case.
This will have an impact on how coulombs are defined (along with pretty
much all other electromagnetic units).
See also: "xapsnidu", "dikckulome".
Tl;dr: The electron should be measured to have positive charge by Lojbanic