Leakage resistance in a capacitor

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Discussion Overview

The discussion revolves around the calculation of leakage resistance in a capacitor, specifically focusing on a 100pF parallel-plate capacitor with a mica dielectric. Participants are exploring the relevant equations and concepts needed to solve the problem, including capacitance and resistance formulas.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant seeks the equation to calculate the leakage resistance (RL) of a capacitor, given its capacitance, dielectric properties, and resistivity.
  • Another participant suggests using the formula for capacitance of an ideal parallel plate capacitor to aid in finding the resistance.
  • A participant expresses confusion regarding the relationship between capacitance and resistance, indicating a lack of familiarity with electrical concepts.
  • There is a mention of the formula for capacitance (C = εr εo * A / d) and its relevance to the problem, although the participant notes they already have the capacitance value.
  • One participant asks if another has found the formula needed to solve a similar question, indicating ongoing uncertainty in the group.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the specific formula needed to calculate the leakage resistance. There is ongoing confusion and a lack of clarity regarding the relationship between the formulas for capacitance and resistance.

Contextual Notes

Participants have not provided specific values for the area (A) or distance (d) between the plates, which may be necessary for calculations. The discussion also reflects varying levels of familiarity with electrical concepts among participants.

Who May Find This Useful

This discussion may be useful for students or individuals studying electrical engineering or physics, particularly those encountering concepts related to capacitors and resistance for the first time.

Dan_tanner
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Homework Statement



I am trying to find the relevant equation to to solve the following problem,

RL= leakage resistance measured across the dielectric

A 100pF parallel-plate capacitor has a mica dielectric of relative permittivity \epsilon[/r]=12 and a resistivity of \rho=10^14\Omega m. <br /> <br /> I want to calaculate the leakage resistance of this capacitor.<br /> <br /> <br /> <h2>Homework Equations</h2><br /> <br /> <br /> <br /> <h2>The Attempt at a Solution</h2><br /> <br /> The previous question wanted to know the area and distance between the plates of the capacitor, i think that this has something to do with the answer to the question,<br /> <br /> I have solved this!<br /> <br /> I think i have all the relevant information to have an atempt at the answer but don&#039;t know and can&#039;t find the equation, <br /> <br /> I am not sure if Resistance R = rhol/A has anything to do with it because it states resistivity is \rho = 10^14 \Omega m<br /> <br /> this has thrown me??<br /> <br /> I can&#039;t find anything that points me in the right dierction in my books or course work.
 
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You're missing a needed formula here which gives you the capacitance of an ideal parallel plate capacitance. Use that and your resistance formula to find R.
 
Hello Defender,

Thanks for the reply, I am still not sure, i don't really understand what you are on about? I am all mechanical ad never had to do electrical before.

Are you on about C= epsilon r epsilon o * A / d

If so, this is the formula for finding C which is in farads which i have already been given as100pF
 
You can transpose the formula to to obtain an expression to help you calculate resistance from the other formula.
 
Dan_tanner said:
Hello Defender,

Thanks for the reply, I am still not sure, i don't really understand what you are on about? I am all mechanical ad never had to do electrical before.

Are you on about C= epsilon r epsilon o * A / d

If so, this is the formula for finding C which is in farads which i have already been given as100pF

Dan,

Did you ever get the formula as I am stuck on asimilar question
 

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