# What does the electric field for twin capacitors in series look like

I know what it looks like for a parallel plate capacitor, but not for two in series. I'm not currently sure if the field goes constantly from outer plate to outer plate or somehow "pauses" over the connecting wire. If anyone can describe it or even show a simulation then that'd be great.

Capacitors in series

Electric field for one parallel plate capacitor (middle picture)

• The answer to this question heavily depends on the details you wanna go into. Hint: start with two discharged caps (i.e. all voltages are zero), then connect the battery and wait a lot of time. And remember that in a metal the electric field is not present. Like the metal the wires are made of. Sep 3, 2015 at 20:34
• The middle section is completely floating, and so has an arbitrary DC voltage/charge. Are you assuming it has been set to the midpoint of the two end voltages? Sep 3, 2015 at 20:42
• Yeah I think so just like it would be in the circuit diagram above; if the battery has voltage V then the wire is at V/2, if that matters. Sep 3, 2015 at 21:00
• @Vladimir; ok good hint thx. Sep 3, 2015 at 21:02
• If the capacitors are identical in every way and suspended in a(n) homogenous medium, then the shape of their fields will be identical. Sep 3, 2015 at 23:55

## 1 Answer

I've tried to do a simulation for one and two parallel plates, shown in the pictures below. In the two-capacitor picture there is a wire connecting them that is hard to see.

• The voltage is the same across both the single and the twin pair (9V)
• Notably the electric field strength between the plates becomes very consistent when the relative permittivity of medium between the plates increased from 1 to 2.
• The field strength between the plates for a single capacitor is twice what it is for two of them. This is the main thing I was interested in.
• The field is well contained between the plates.
• I included a voltage picture for the twin capacitors.

This was in aid of trying to understand about two capacitors in series having a lower overall capacitance than one.