Where is the Error in this AC/DC Circuit Analysis?

In summary, the conversation discusses the setup of a circuit with a DC voltage and an oscillating source. V is the voltage between two resistors, I is the current exiting the capacitor, and I1 and I2 are the currents through the two resistors. The equations for I1 and I2 are given, along with a combination of all the equations. The constant term can be eliminated and the sign on the right hand side can be chosen to give a homogenous solution. However, there is an inconsistency with the sign or direction of I1, which is causing confusion. The conversation ends with a request for help in identifying where the error may be.
  • #1
pierce15
315
2
IMG_1481801473.286857.jpg


See picture, sorry that it's huge. V1 is a DC voltage and there is also an oscillating source of frequency omega. Let V be the voltage between the two resistors, I be the current exiting the cap, and I1 and I2 be the currents through the 2 resistors. Then we have: ## I_1 = (V - V_1) / R_1## , ## I_2 = V / R_2##, ##I_1 + I = I_2 ##, and ## I = - C \frac{d}{dt} (V - V_0 \cos (\omega t)) ##. Combining gives ## -C \frac{d}{dt} (V - V_0 \cos (\omega t )) = V / R_2 - (V - V_1)/ R_1 = V( 1/R_2 - 1/R_1) + V_1 / R_1##. The constant term can be eliminated with a substitution, and then the sign on the right hand side can be chosen to give a homogenous solution of the form ##e^{ax} ## with ##a > 0##, by choosing ##R_1## accordingly. This obviously makes no sense. Can someone see where I am setting this up wrong?
 
Last edited:
Engineering news on Phys.org
  • #2
The sign or direction of I1 looks inconsistent.
 
  • #3
Sorry for not updating. The current across R1 is inconsistent. Thanks.
 
  • Like
Likes mfb

Related to Where is the Error in this AC/DC Circuit Analysis?

1. What is the difference between AC and DC current?

AC (alternating current) is a type of electrical current that constantly changes direction, while DC (direct current) flows in only one direction. AC is typically used for transmitting electricity over long distances, while DC is used for powering small devices.

2. Can a circuit have both AC and DC current?

Yes, a circuit can have both AC and DC current. This is known as a mixed or hybrid circuit, and it is commonly used in electronic devices.

3. How do AC and DC current interact in a circuit?

In a mixed circuit, AC and DC current can interact in a few different ways. For example, they can be used to power different components in the circuit, or they can be combined to create a specific voltage or current output.

4. What are the advantages of using a circuit with both AC and DC current?

A mixed circuit offers the advantages of both AC and DC current. AC is better for long distance transmission, while DC is more efficient for powering small devices. By combining both types of current, a circuit can be designed to be both efficient and versatile.

5. Are there any safety concerns when working with a circuit with both AC and DC current?

Yes, there are some safety considerations when working with a mixed circuit. It is important to understand the different properties and risks associated with AC and DC current, and to use proper safety precautions when handling and testing the circuit.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
6
Views
1K
  • Electrical Engineering
Replies
3
Views
922
  • Introductory Physics Homework Help
Replies
1
Views
349
  • Introductory Physics Homework Help
Replies
13
Views
353
  • Electrical Engineering
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
6
Views
295
  • Introductory Physics Homework Help
Replies
16
Views
1K
Replies
2
Views
818
  • Electrical Engineering
Replies
10
Views
2K
  • Electrical Engineering
Replies
7
Views
2K
Back
Top