A current varying in strength without any abrupt transition from action
to inaction, as in the make and break current. The current may be
continually changing in direction, and hence,
of necessity, may pass through stages of zero intensity, but such
transition must be by a graduation, not by an abrupt transition. Such
current may be represented by a curve, such as the curve of sines. It is
evident that the current may pass through the zero point as it crosses
the line or changes direction without being a make and break current.
When such a current does alternate in direction it is sometimes called a
“shuttle current.” The ordinary commercial telephone current and the
alternating current is of this type.