Electric field across a parallel plate capacitor

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Homework Help Overview

The discussion revolves around the electric field across a parallel plate capacitor in the context of a circuit that includes a potential source, a resistor, and the capacitor itself. Participants are exploring how the arrangement of these components affects the electric field calculation.

Discussion Character

  • Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants are examining two formulas for the electric field: E = (V - IR)/L and E = V/L, questioning under what conditions each applies based on the circuit configuration. There is a focus on whether the resistor is in series or parallel with the capacitor and how this impacts the electric field as the capacitor charges.

Discussion Status

The conversation is active, with participants clarifying the implications of circuit configurations on the electric field. Some have suggested that the initial condition of the circuit affects the electric field, while others note that once the capacitor is fully charged, the electric field simplifies to E = V/L.

Contextual Notes

Participants are considering the effects of circuit setup, specifically the arrangement of the resistor relative to the capacitor, and how this influences the electric field calculations. There is an acknowledgment of the changing conditions as the capacitor charges.

johnj7
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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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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.
 

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