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capacitor problem

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nkodogi

New Member
I have this capacitor problem that I am thinking about for a few days now.

I have two capacitors charged separately:
Cap1: 6uF, 4V and Cap2 3uF, 1V.
Then they are connected in such a way as the positive terminal of one is connected to the positive terminal of the other.

Ao-----(-)| |(+) ----(+)| |(-)------oB

----- represents the wire. (-) (+) the polarity.

What type of connection is that?
It cannot be in series is that correct?
What is it going to happen?

The voltage difference between A and B is 3V.
So the capacitance of the combination will be
C = Q(total)/v = 27/3 = 9uF.
This is not the series capacitance.
The series capacitance is 2uF.

Are the capacitors in parrallel?
How could that be since their voltages are different.

This is a circuit class problem that I am trying to solve.

Any help please?
 

mattg2k4

New Member
This is certainly a confusing setup.

It doesn't look like parallel or series to me. Parallel would mean both the positive leads are conencted, and negative leads are connected. Series would be positive of one cap connected to negative of another. I'm not sure what the effects of your combination will be. I'm not even sure it will have an effect, since the positive leads aren't connected to anything. If the capacitors are nonpolar, it would be series, but if they are polar, then I'm stumped.

What is this setup for?
edit: nm, reread your post and saw it was a class problem.
 

isaacj

New Member
It's a series circuit.

What are you trying to determine in this circuit? The voltage that would be produced when they are discharged? Said voltage's polarity?
 

Gene

New Member
What you have created is a non-polorized cap.

Yes they are in series. Non-polorized caps (manufactured) and combos like your circuit (which result in high capacitance for physical size) are used for cross over circuits - among other things.

You may want to re-think your calculations.
 

isaacj

New Member
Gene said:
What you have created is a non-polorized cap.

... and combos like your circuit (which result in high capacitance for physical size)...
Do the capacitances of the two add up or do the calculations for series caps still apply?
 

lavenatti

Member
The calculations for series caps would apply.

If they are polarized, be careful of the voltages you use. They won't hold up to the rated voltage since one will always be hooked up backwards.
 

Dean Huster

Well-Known Member
Regarding the "non-polarized cap" myth:

Caps connected in reverse-series are often touted as being the equivalent of a "non-polarized" cap. I'll bet that if you connect those two caps up like that and slap a dc voltage across the circuit, you'll find polarities on one of the caps that you (or it) won't like. It takes some steering diodes across the caps to create a non-polarized cap circuit from two standard electrolytic caps.

Dean
 

Gene

New Member
This "creation" is closer to a non-polorized cap than anything else I could think of - hopefully no one will "slap a DC voltage across it" such that the caps become unhappy. I did not mean to confuse anyone so, for the record, if you have a circuit that calls for a non-polorized cap - go buy one. On the other hand, if you need a polorized cap, use that and observe the polarity.

Actually, I read the post as a teacher's 'power trip' to confuse those students who were concerned enough about getting a good education that they would actually spend time thinking it through.
 
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