Solving phasor circuit with unknown dep. current src

In summary, combining a capacitor and resistor in parallel creates a voltage of 4 volts at 0 degrees.
  • #1
256
18

Homework Statement


Selection_029.png


Homework Equations


V=IR

The Attempt at a Solution


I try to simplify the circuit by combining the capacitor and 2ohm resistor in parallel, Z = 1-j. Then I add the inductor to get Z = 1. Knowing the current across the resistor, 2(0d) I find the voltage across the 5 ohm resistor (2(0d)). So 2/5(0d).

The real part is 0.4 (correct). The imaginary part is 0 (incorrect)??

The answer for the imaginary part is 0.4 But I don't get this in my attempt.
 
Last edited:
Physics news on Phys.org
  • #2
x86 said:
I try to simplify the circuit by combining the capacitor and 2ohm resistor in parallel, Z = 1-j. Then I add the inductor to get Z = 1. Knowing the current across the resistor, 2(0d) I find the voltage across the 5 ohm resistor (2(0d)). So 2/5(0d).
Combining the capacitor and 2 Ohm resistor is a good start. But then adding the inductor's impedance to it at that point is not so good.

You see, you may know the current through the resistor thanks to having its potential difference, but there is also the current through the capacitor to consider. What must the current be through the combined impedance (cap || resistor) in order for the potential difference across it to end up being 4V @ 0°?
 
  • #3
gneill said:
Combining the capacitor and 2 Ohm resistor is a good start. But then adding the inductor's impedance to it at that point is not so good.

You see, you may know the current through the resistor thanks to having its potential difference, but there is also the current through the capacitor to consider. What must the current be through the combined impedance (cap || resistor) in order for the potential difference across it to end up being 4V @ 0°?

If I'm not misaken, after combining the resistor and capacitor, I know the voltage through them both is V1. Then by dividing by their combined impedence, I get the current through these two elements, which I draw a black box.

So now I know the current through this black box. I combine the impedence of the black box and inductor, multiplying by the current, to get the voltage. Now I know the voltage across the current source and the 5 ohm resistor (they are in parallel).
 
  • #4
x86 said:
If I'm not misaken, after combining the resistor and capacitor, I know the voltage through them both is V1. Then by dividing by their combined impedence, I get the current through these two elements, which I draw a black box.

So now I know the current through this black box. I combine the impedence of the black box and inductor, multiplying by the current, to get the voltage. Now I know the voltage across the current source and the 5 ohm resistor (they are in parallel).
Yes, that would work fine.
 

Related to Solving phasor circuit with unknown dep. current src

1. What is a phasor circuit?

A phasor circuit is an electrical circuit that contains sinusoidal signals or components. It is often used to analyze the behavior of alternating current (AC) circuits.

2. How do you solve a phasor circuit?

To solve a phasor circuit, you need to first convert all of the sinusoidal signals and components into phasors, which are complex numbers that represent the magnitude and phase of the signal. Then, you can use Kirchhoff's laws and other circuit analysis techniques to solve for the unknown variables.

3. What is an unknown dependent current source?

An unknown dependent current source is a type of circuit element that is dependent on other variables in the circuit, such as voltage or current. It is represented by a symbol with a diamond-shaped arrow pointing towards the current source, and its value is usually given in terms of a variable or function.

4. How do you handle an unknown dependent current source in a phasor circuit?

To handle an unknown dependent current source in a phasor circuit, you can use the same techniques as you would with any other unknown variable. You can apply Kirchhoff's laws and other circuit analysis techniques to solve for the unknown current source and then convert the solution back into phasor form.

5. What are some common mistakes when solving phasor circuits with unknown dependent current sources?

Some common mistakes when solving phasor circuits with unknown dependent current sources include forgetting to convert all signals and components into phasors, not properly applying Kirchhoff's laws, and using incorrect algebraic manipulations. It is important to double check all steps and make sure they are consistent with the principles of phasor analysis.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
26
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
8
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
20
Views
3K
  • Engineering and Comp Sci Homework Help
Replies
4
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
6
Views
878
  • Engineering and Comp Sci Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
230
  • Engineering and Comp Sci Homework Help
Replies
7
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
3
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
19
Views
1K
Back
Top