Someone is missing the point. AC voltages and currents are often represented as complex numbers (phasors). For example, the expressions,
V = Vpk(cos(phi) + jsin(phi))?trigonmetric or circular form
= Vpk(e^j(phi))?exponential form
= Vrms @ phi?polar form
are all equivalent.
Where ?phi? is the angle of lead relative to the reference axis which is the positive x axis in the xy plane. A phasor lying along this axis and pointing the right is at 0 degrees.
[Tang, AC Circuits, pp 124?126, Intl. Textbook Co., 1960]
Although we often assume zero phase angles to voltages and currents for convenience, there is no rule that says we have to. I might for example assign angles of 30, -90, and ?210 to a set of 3-phase voltages, and this would be perfectly valid.
We can make the vector rotate by inserting ?wt? in the argument.
v(t) = Vpk(cos(wt + phi) + jsin(wt + phi))
Again, ?phi? is the angle of lead relative to the reference axis. A negative value of phi indicates a phase lag relative to zero degrees.
It is my understanding that a scope synched at time zero would show Vpk(sin(wt + phi). That is, the trace would show the imaginary part of the phasor. This is contrary to what I have been thinking, and that is why I asked the question.
To do this, one would have to generate an external synch pulse at time zero, then the trace would show.
Vpk(sin(wt +phi))
One could also use delayed synch to get the proper display.
In practice, this is seldom done, but it is often done on paper to explain the relationship between a phasor and its corresponding instantaneous value.
P.S. The jokers should start their own thread.