Electric field across a parallel plate capacitor

• johnj7
In summary, the electric field across the capacitor depends on the circuit setup. If the resistor is in series with the capacitor, then the electric field can be expressed as E = (V - IR)/L initially, but will become E = V/L once the capacitor is fully charged. If all components are in parallel, then the electric field will always be E = V/L.

johnj7

Hello,

If I had a potential source (V) , a resistor R, and a parallel plate capacitor,

would the Electric field across the capacitor become

E = (V - IR)/L

L = distance between capacitor

or would the electric field simply become E = V/L

??

thank you!

How is the circuit set up? Your E = (V - IR)/L would be correct for a purely series circuit. But the current would be zero (or quickly become zero as the capacitor charges) so your second formula is then correct.

johnj7 said:
Hello,

If I had a potential source (V) , a resistor R, and a parallel plate capacitor,

would the Electric field across the capacitor become

E = (V - IR)/L

L = distance between capacitor

or would the electric field simply become E = V/L

That very much depends on whether the resistor is in series or in || with the capacitor doesn't it?

Ah ic, oh okay I understand now.

so if in series,
clearly initially it is

E = (V-IR) /L
but after the capacitor is fully charged then E = V/L

however if in parallel from the start then

E = V/L, always

would this be correct?

If the V, R and C are all in parallel then they all have the same potential V.