What Is the Relative Permittivity of the Dielectric in This Capacitor?

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SUMMARY

The discussion focuses on calculating the relative permittivity of a dielectric material in a capacitor with two circular parallel plates, each 12.5 mm in diameter and 3 mm thick, resulting in a capacitance of 10 nF. The formula used is C = (relative permittivity) * (A/d), where A is the area of the plates and d is the separation distance. The area A is calculated using the formula for the area of a circle, and the relative permittivity can be derived from the rearranged capacitance formula. The discussion also addresses whether the calculated permittivity is an underestimate or overestimate when considering the finite thickness of the plates and insulation.

PREREQUISITES
  • Understanding of capacitor fundamentals, including capacitance and dielectric materials.
  • Familiarity with the formula C = (relative permittivity) * (A/d).
  • Basic knowledge of geometry, specifically calculating the area of a circle.
  • Awareness of SI units and their application in electrical engineering.
NEXT STEPS
  • Research how to calculate the area of a circle and its application in capacitor design.
  • Learn about the impact of dielectric thickness on capacitance and permittivity.
  • Explore different dielectric materials and their relative permittivity values.
  • Study the effects of insulation on capacitor performance and accuracy in calculations.
USEFUL FOR

Electrical engineers, physics students, and anyone involved in capacitor design and analysis will benefit from this discussion.

Tom555
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Consider a commonly-used capacitor made from two circular
parallel plates with a ceramic dielectric between them. The plates have 12.5 mm diameter and the whole thing is 3 mm thick with a capacitance of 10 nF. Neglecting the finite thickness and extent of the plates, what
relative permittivity must the material between the plates have to provide this capacitance?
Allowing for the finite thickness of the plates, and of the insulation wrapping the outside of
the whole thing, is this an underestimate or overestimate of the permittivity?

I'm really not sure how to start at all. Without filling in details, can someone please explain how I would go about this problem?
 
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Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
 
In SI units,
C=(relativity permittivity)*A/d
 

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