# Electric field across a parallel plate capacitor

#### 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!!

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#### Delphi51

Homework Helper
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.

#### LowlyPion

Homework Helper
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?

#### johnj7

Ah ic, oh okay I understand now.

so if in series,
clearly initially it is

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

however if in parallel from the start then

E = V/L, always

would this be correct?

#### Delphi51

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

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