Timeline for How is a capacitor in series with a resistor and capacitor in parallel calculated?
Current License: CC BY-SA 4.0
29 events
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| Apr 15, 2021 at 18:16 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Dec 14, 2020 at 5:07 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Aug 7, 2020 at 11:04 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Mar 26, 2020 at 5:02 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Mar 3, 2020 at 14:36 | comment | added | hanslhansl | Thank you so much @ElliotAlderson. You helped me rectify wrong assumptions i somehow came to. I will create a new question with a correct circuit. | |
| Mar 2, 2020 at 22:00 | comment | added | Elliot Alderson | Yes. You need some resistance in series with the voltage source. | |
| Mar 2, 2020 at 15:58 | comment | added | hanslhansl | @ElliotAlderson So if i specified an ESR for both of these caps the circuit could be analyzed? | |
| Feb 28, 2020 at 13:05 | comment | added | Elliot Alderson | Yes, in real life you could do that. But the schematic you have presented is not a suitable model for "real life". It is lacking critical elements such as the ESR of the capacitors themselves. As drawn the schematic you present and the scenario you describe can not be analyzed using conventional circuit techniques. | |
| Feb 28, 2020 at 12:05 | comment | added | hanslhansl | What do you mean with "violated"? I could build this circuit in reality and the capacitors would get charged right after connecting the circuit to the voltage source, wouldn't they? @ElliotAlderson | |
| Feb 25, 2020 at 23:57 | comment | added | Elliot Alderson | If you assume that the initial voltages across the capacitors are 0V each then the circuit is a nonsense circuit and can not be analyzed. At the instant when the voltage source is connected the capacitor voltages will still be zero, and KVL will be violated around the outer loop. | |
| Feb 25, 2020 at 19:33 | comment | added | hanslhansl | @ElliotAlderson ^ | |
| Feb 24, 2020 at 21:09 | history | edited | hanslhansl | CC BY-SA 4.0 |
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| Feb 24, 2020 at 21:06 | comment | added | hanslhansl | I understand. So my goal is to calculate the voltages etc assuming the capacitors are initially discharged. I guess i was missing the right vocabulary. How would I need to draw the circuit to resemble what i want? With a switch? And now that you know what i want is it possible to do a transient analysis on this circuit? @ElliotAlderson | |
| Feb 24, 2020 at 20:49 | comment | added | Elliot Alderson | The circuit you show is invalid for the case of "hooking up for the first time" if you assume that the capacitors are initially discharged. At the instant of connection the capacitors will have the same voltage across them (0V) but KVL says their total voltage must equal the supply voltage. So, you are missing some important information or some important circuit elements. | |
| Feb 24, 2020 at 20:46 | comment | added | Elliot Alderson | Well. you didn't say anything about "hooking up the circuit for the first time". A DC problem assumes that voltages and currents never change. | |
| Feb 24, 2020 at 20:35 | comment | added | hanslhansl | @ElliotAlderson i forgot to add your name in the comment above. | |
| Feb 24, 2020 at 20:27 | comment | added | hanslhansl | I understand. But closing the circuit with the switch is essentially the same thing as hooking the circuit up for the first time right? For a short period afterwards the charge in the caps rises until it (almost) hits 100%. At that point the caps have an infinite resistance and there is (almost) no current. Right? Now what i want to calculate is the short period after closing the switch/hooking the circuit up when current and charge is changing massively. If that is a transient analysis thats what i want to do. I thought this formula is the one to use and i just need the proper way of using it | |
| Feb 24, 2020 at 20:05 | comment | added | Elliot Alderson | The wikipedia entry is for a circuit that includes a switch. Your circuit has no switch. The switch effectively causes the applied voltage to change with a step function, and this is properly called a "transient analysis" rather than a dc solution. | |
| Feb 24, 2020 at 18:17 | comment | added | hanslhansl | Wikipedia mentions it as the DC formula @ElliotAlderson | |
| Feb 24, 2020 at 17:01 | comment | added | Elliot Alderson | No, that's not the formula for a capacitor connected to dc...that's the formula for a capacitor connected to a voltage source where the voltage changes with a step function at t=0. | |
| Feb 24, 2020 at 16:38 | comment | added | hanslhansl | If you are talking about this formula I(t)=V_0/Re^(-t(RC)) yes i do. I also know how it is applied to 2 caps in series. It's the parallel connection combined with the cap in series that i don't know about. @ElliotAlderson | |
| Feb 24, 2020 at 15:04 | comment | added | Elliot Alderson | Do you know how much current flows through a capacitor if a constant dc voltage is applied? That's the key to solving this problem. | |
| Feb 24, 2020 at 13:12 | comment | added | hanslhansl | You are right i forgot that. It's 10 volt dc. I edited the question for clarification too. @ElliotAlderson | |
| Feb 24, 2020 at 13:10 | history | edited | hanslhansl | CC BY-SA 4.0 |
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| Feb 23, 2020 at 22:15 | review | Close votes | |||
| Mar 1, 2020 at 3:05 | |||||
| Feb 23, 2020 at 21:59 | comment | added | Elliot Alderson | You need to tell us how the voltage source behaves as a function of time. Does it supply a dc voltage? Does the voltage change suddenly from one value to another? Does the voltage source provide an ac voltage at a fixed frequency and constant amplitude? | |
| Feb 23, 2020 at 20:43 | comment | added | Andy aka | Well you are going to get infinities at t = 0 so there's a clue. | |
| Feb 23, 2020 at 19:26 | answer | added | Nabla | timeline score: 1 | |
| Feb 23, 2020 at 19:02 | history | asked | hanslhansl | CC BY-SA 4.0 |