# Homework Help: How to tell if the components are in parallel or series

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1. Oct 3, 2014

### Emspak

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

I need to work out the impedance of this notch filter, and what I really need is to know how to read the diagram, because if I can do that the rest isn't so hard. The diagram looks like this (I don't know if this uploaded right)

So really, all I am trying to do is tell if the inductor and capacitor should be considered in series or parallel, and if the resistor should be trated as in series with another "resistor" (the parallel sum of the inductor and capacitor) or if I should treat the resistor as in parallel with both the inductor and capacitor. Reading diagrams is elementary I know but sometimes a little explanation goes a long way, and I suspect that I should treat the inductor and capacitor as a mini-series in parallel with the resistor but I wanted to make sure.

I don't want the answer or anything, jut a note as to where to get the ball rolling.

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2. Oct 3, 2014

### ShawK

Doesn't the circuit (for a lack of better word) or the path taken by the charge change based on the impedance of the filter?

3. Oct 3, 2014

### Emspak

I am honestly not sure, I was just told to find the impedance. I have zero idea of what you mean here.

4. Oct 3, 2014

### ShawK

A notch filter is a bandstop filter that stops certain frequencies while letting others pass. I have a feeling the impedance is a direct function of the range of frequencies it stops. And this range should be fairly easy to find although I forgot the exact formula

5. Oct 3, 2014

### Emspak

I get what a notch filter does. That isn't the problem. I need to be able to read the diagram is all, that's what I am asking so I can do the derivation correctly. I am trying to discover if I am reading it correctly or not! I don't have much experience doing it which is why I asked the question.

6. Oct 4, 2014

I do follow certain rules in order to check whether elements are in series or parallel.

For elements to be in series:-

If two elements are connected at only one end.
Current flowing in elements must be same and their voltage drops different(depending on resister values).

For elements to be in parallel:-

If two elements are connected to each other by both ends.
Voltage across both the elements is same and their currents different (depending on resistance values).

7. Oct 4, 2014

In your circuit inductor and capacitor are connected at one end so they are in series.

8. Oct 4, 2014

### Staff: Mentor

The 3 elements are all in series. It would help you to see how this works if you were to mark the input and output signals of this filter showing how it is used.

9. Oct 4, 2014

### Emspak

@lazyaditya and NascentOxygen -- thanks, that is what I was trying to verify. Input is on the left, BTW, and output is on the right. The reason I was getting confused was when I looked up the actual formulas they looked as though the elements were in parallel; they weren't it was just the way they'd arranged the variables. (Some were fractions). Now that I know that the whole thing is simpler.

@lazyaditya I suspected that the "both ends" rule applied here but I wasn't sure because if you connect a load that is in parallel with the inductor and the capacitor. So it looks like a parallel connection from that point of view.