Is that definition of "DC" written in stone (i.e. fundametnally true)
or as defined by convention? How is a sine wave operating as all
postive voltages not yielding a current (albeit variable) of a single
polarity, single direction that does not alternate? Isn't saying it is
an "alternating current with a dc offset" a rather queer way of saying
things since there actually is no (net) alternating (i.e.
bi-directional) current flow?