Parasitic Resistance in capacitors/inductors

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The discussion revolves around calculating the frequencies at which the current through a capacitor's parasitic resistance is a specific percentage of the current through the capacitor itself. Participants express uncertainty about the equations needed for the calculations, particularly regarding capacitive reactance. Clarification is provided that the current is equal when the reactance of the capacitor matches the equivalent resistance. Additionally, the conversation shifts to how to approach similar calculations for inductors, noting that losses can be modeled differently depending on whether they are series or parallel resistances. The thread concludes with a focus on understanding these modeling approaches for both capacitors and inductors.
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Homework Statement
A 82 nF capacitor has a parasitic parallel resistance Rp = 600 kΩ.
If a voltage V = Vmsin(ωt) is applied, as shown in the diagram, find the frequencies at which:
1. The current amplitude through the parasitic resistance is 1% of the current amplitude
through the capacitor.
2. The amplitudes of the currents through the resistor and the capacitor are equal.


The attempt at a solution

I don't even know where to start with the question and I do not know what equations are needed to get the answer. Any help from people would be great.
 
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The current is equal when the reactance of the capacitance is equal to that of the (equivalent) resistance.

Do you know the formula for capacitive reactance.
 
ok thanks i got the answer but how would you go about it if it was an inductor instead?
 
dudforreal said:
ok thanks i got the answer but how would you go about it if it was an inductor instead?

That would depend upon whether the inductor losses were modeled by a series resistance or an equivalent parallel resistance. Copper losses are usually modeled with a series resistance whereas core loses are usually modeled with an equivalent parallel resistance.
 
ok thanks :smile:
 

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