Adding Capacitors, why do I add it like this?

[flyingpig]

Homework Statement

Let's say I have a circuit that looks like that below


http://img262.imageshack.us/img262/9260/97438850.th.png

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Questions

Now I got two questions

a) If the middle (the one in 180 degrees) capacitor were not there, would still treat the ones on the side as a series? In other words would you add the two capacitors on the same side a series and then add the two across each other as a parallel?

b) It kinda relates to one, how come when you add the ones on the side, it becomes 180 Ceq?

I mean why does it look like this after you add the ones on the edge?

http://img262.imageshack.us/img262/9260/97438850.th.png

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Instead of

http://img340.imageshack.us/img340/1629/32604437.th.png

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[SammyS]

(a) Yes.

(b) What do you mean by "180 Ceq" ?

 

[flyingpig]

This is 180 =, this is 90 ||

 

[tedbradly]

This is 180 =, this is 90 ||

In your first example of adding them (the one you imply is correct in your mind, picture 2), you haven't actually changed anything relative to the initial configuration, picture 1. Thus, your point becomes a task of interpretation to uncover your intentions for us readers, and I will make that extrapolative leap. Forgive me if the thoughts I presume you have are not yours, and take no insult from the presumption.

Are you asking why people normally draw the new circuit, after doing two series combinations on each side, with 3 capacitors that are oriented as = instead of 1 = and 2 || as you've drawn in picture 3?

The answer is standardization. Seeing familiar structures helps to reduce errors. For example, instead of using possibly quicker laws of cosines or sines in some vector problems in physics, you may always take the sure-fire way you understand and simply break up the components and proceed from there. Similarly, there is no reason to draw your circuits differently all the time. Draw it as you see it most often drawn even though that standard, rectangular form may be slower to draw or less convenient to draw. Doing so will help reduce errors (assuming you've grown accustomed to that look).

Anyway, both circuits, 3 and the one I've suggested as your intended 2, are equivalent. There is nothing 'wrong' about your circuit. Due to the often standardized appearance of circuit diagrams, though, you may miss a parallel or series combination that would become obvious if you redrew it in 'standard' form.

For beginners especially, I recommend always redrawing the circuit to match your comfort zone.

 

[flyingpig]

I am sorry, but I have no idea what you are trying to say...but I am feeling that I am right?

 

[gneill]

1. Capacitors are either in series or they are not. It is strictly a matter of their lead interconnection; Two leads, one from each capacitor, connected and nothing else connected to that junction means they are in series. The only exception is if their other leads are also connected to each other -- then they're in parallel.

2. Capacitors are either in parallel or they are not. It is strictly a matter of their lead interconnection; each lead of each capacitor must be connected to exactly one lead of the other capacitor. They are paired.

3. The orientation of a schematic symbol on a diagram makes no difference to function. It is strictly a matter of aesthetics in presenting a lucid diagram conforming to accepted norms.

4. The length, twists, turns, or other geometric convolutions of otherwise continuous lines representing interconnections makes no difference to function -- one unbroken conductive path (zero resistance) represents one node in a circuit.