Area of a Parallel Plate capacitor. Pi*r^2?

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SUMMARY

The discussion clarifies the calculation of the electric field in a parallel plate capacitor, specifically addressing the area used in the formula. The area is defined as πr², where r is the radius of one circular electrode. This is because the charge resides on the electrodes, not in the space between them. The misconception that the area should be the product of the length of one electrode and the distance between electrodes is corrected, emphasizing the importance of the electrode's surface area in determining the electric field.

PREREQUISITES
  • Understanding of electric fields and charge density
  • Familiarity with the formula E = σ/ε₀
  • Knowledge of parallel plate capacitor design
  • Basic geometry, specifically area calculations for circles
NEXT STEPS
  • Study the derivation of the electric field for parallel plate capacitors
  • Learn about charge distribution on conductors
  • Explore the differences between circular and rectangular capacitor designs
  • Investigate the effects of dielectric materials on capacitor performance
USEFUL FOR

Physics students, electrical engineers, and anyone studying capacitor design and electric fields will benefit from this discussion.

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Hi,

I was just going through a question in my Physics textbook today. In calculating the electric field (E=sigma/epsilon0) ... sigma = charge density = q/Area ... they have used the area as pi*r^2, I can't understand why this was done? shouldn't the area of the parallel plate capacitor be length of one electrode * distance between electrodes?

Hope I'm making sense!
 
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No, the area that we use here is the area of one of the electrodes (circular in this case, apparently). The charge resides on the electrodes, not in the space between them.
 
Hmm, makes sense. Thanks mate!
 

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