The following EJS simulation show you the voltage/current as function of time for different combinations.
At least one resistor R1 is in series with another resistor, or in series with a capacitor (RC circuit) or in series with a diode.
The dot along the loop simulate the movement of electron motion (average).

VIEW or DOWNLOAD ejs xml source
then click to translate strings for selected locale.

Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop.