Sorry, I'm already ashamed to ask for your help. But I'm feel that I needed in some hints about how to imagine alternating current. I really realize I have trouble with it during reading this document (full but old version is here). There is image on p.29:
At first, this simple circuit consisting of a battery and a resistor was in some steady state with constant voltage and current all around. Then source voltage is doubled. And there is this transient phase on the image during which a new voltage is forming. Pluses/minuses represent surface charges on the wires. The change in charge distribution travels like a wave-front through the circuit with speed of light.
I explicitly divide all these states apart. Like, 1st steady state with some current in accordance with Ohm's law > transient phase > new steady state after doubled voltage reached resistor with increased current in wires and the resistor.
My problem is that when I try to image AC voltage source instead of DC the mess begins. Since, roughly speaking, there is no steady states now, voltage and charge distribution on the wires is constantly changing. Because of this its hard for me to imagine alternating current in the circuit.
Maybe it would be a little easier for me if I knew the following. On the image above, there are 2 regions, behind "wave front", where a new doubled voltage has already been formed and ahead of it, where voltage is still old.
So my question is about currents in these regions. Is there in the region behind "wave front" already increased current and its value satisfying I = V/R and ahead the front, correspondingly, old value of current ?
If so, I can imagine AC more or less as follows: as voltage propagates down the wires it cause appropriate currents (according to Ohm's law), lets say, in vicinity of wave front. And since length of wires is small in this case, one can think as in some instant of time wave front "ran" through all wire and reach it end. And so we have some concrete equal value of potential for entire length of the wire and appropriate current's value in it.
If this is a wrong idea then I'm lost and would like to hear some tips about how to imagine it. Thanks for the help.