# Homework Help: Parasitic Resistance in capacitors/inductors

1. Sep 18, 2011

### dudforreal

The problem statement, all variables and given/known data
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.

2. Sep 18, 2011

### uart

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.

3. Sep 18, 2011

### dudforreal

ok thanks i got the answer but how would you go about it if it was an inductor instead?

4. Sep 18, 2011

### uart

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.

5. Sep 18, 2011

ok thanks