2-Capacitor, 2-Resistor Parallel RC Circuit with Switch

In summary: Anyway, if we start with the assumption that the capacitors are initially uncharged then the final voltages will be the same regardless of the sequence of events. If the switch is first opened and the capacitors are then left open for a long time they will discharge and reach their final voltage. If the switch is first closed and the capacitors are then left open for a long time they will charge and reach their final voltage. So, in summary, the final voltages on the capacitors will be the same in both cases, but the discharge time will be different.
  • #1
cep
51
0

Homework Statement



For the attached circuit (which I've drawn rather poorly in GIMP), I need to figure out the charge on each capacitor when the switch has (a) been closed for a long time and (b) been open for a long time.

Homework Equations



Loop and Junction rules, [itex]\Delta[/itex]V=IR, C=Q/[itex]\Delta[/itex]V, 1/Ceq = 1/C1+1/C2

For charging a capacitor, I = (Vemf/R)e^(-t/RC).

For discharging a capacitor, I = -(Qmax/RC)e^(-t/RC)

The Attempt at a Solution



I think I have a conceptual problem in thinking about where the current goes. I'm inclined to think that there is some sort of equilibrium, where the capacitors can discharge through the smaller circuits while the battery charges them through the larger circuits (both when the switch is open and closed). Can anyone help me think about this problem? Preferably sooner...

Thank you!

-CEP
 
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  • #2
Here's the drawing, hopefully, otherwise I can't get the attachment feature to work :/
 

Attachments

  • RC_Circuit.jpg
    RC_Circuit.jpg
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  • #3
When a DC (battery) powered circuit reaches steady state the current in all capacitors will be zero -- they reach their final charge (voltage) and that's it for them. For all intents and purposes they look like open circuits as far as the rest of the circuit is concerned.

For the closed-switch version of the circuit this means that the voltage drops on the resistors of the circuit are going to determine what the final voltages will be on the capacitors.

For the open-switch case the individual capacitor voltages will depend upon the sequence of events. Is the switch first closed for a long time before being opened, thus starting each of the capacitors off with some initial charge, or are we to assume that the capacitors are initially uncharged and the switch already open when the battery power is first applied? The question doesn't specify one way or the other.
 

Related to 2-Capacitor, 2-Resistor Parallel RC Circuit with Switch

1. What is a 2-Capacitor, 2-Resistor Parallel RC Circuit with Switch?

A 2-Capacitor, 2-Resistor Parallel RC Circuit with Switch is an electronic circuit that consists of two capacitors, two resistors, and a switch connected in parallel. This type of circuit is commonly used in electronic devices to filter signals and control the flow of electrical current.

2. How does a 2-Capacitor, 2-Resistor Parallel RC Circuit with Switch work?

In this circuit, the capacitors act as energy storage devices and the resistors control the flow of current. When the switch is closed, the capacitors charge up and store energy. As the capacitors charge, the resistors limit the flow of current. When the switch is opened, the capacitors discharge and release the stored energy.

3. What are the applications of a 2-Capacitor, 2-Resistor Parallel RC Circuit with Switch?

This type of circuit is commonly used in electronic devices such as audio amplifiers, power supplies, and timer circuits. It is also used in radio frequency filters and in electronic systems that require precise timing.

4. What are the advantages of using a 2-Capacitor, 2-Resistor Parallel RC Circuit with Switch?

One of the main advantages of this circuit is that it can easily filter out unwanted signals or noise, resulting in a cleaner output. It is also relatively simple and cost-effective to construct compared to other types of circuits.

5. What are the limitations of a 2-Capacitor, 2-Resistor Parallel RC Circuit with Switch?

One limitation of this circuit is that it can only filter out signals within a certain frequency range. Additionally, the capacitors can only store a certain amount of energy, so if the circuit is overloaded, it may not function properly. It is also susceptible to temperature changes, which can affect the performance of the capacitors and resistors.

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