Help Needed: Solving KCL Equations with Picture Provided

In summary: AIn summary, the conversation discusses applying KCL and KVL equations to solve a circuit problem. The current through the 20kOhm resistor is found to be 2 times i1, and equations are written for the voltage drop across the 5k and 20k resistors. Finally, the KVL equation is solved for i1, resulting in a value of 0.5714mA.
  • #1
xlu2
28
0

Homework Statement



QQ??20130527135512.jpg


Homework Equations



KCL

The Attempt at a Solution



See picture. I got ix=i1. And I am stuck. Would someone please help me?

Many thanks in advance.
 
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  • #2
I got ix=i1

Thats correct. The current through the 20kOhm must be 2i1

How about writing some KVL equations.
 
  • #3
CWatters said:
Thats correct. The current through the 20kOhm must be 2i1

How about writing some KVL equations.

How can I write KVL without any resistors in some loops?

For the leftmost loop: (v2-v1)/5000=0
For the rightmost loop: (v4-v3)/20000=0
 
  • #4
First off you can simplify things..

V1 = V3
V2 = V4

Then write equations for the current through the 5k and 20k.

Edit: oh heck I've given you the current through the 20K already. Just write an eqn for the current in the 5k.

Then using those write equations for the voltage drop across the 5k and 20K.

Then write your KVL equation. Try the outer loop.
 
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  • #5
CWatters said:
First off you can simplify things..

V1 = V3
V2 = V4

Then write equations for the current through the 5k and 20k.

Edit: oh heck I've given you the current through the 20K already. Just write an eqn for the current in the 5k.

Then using those write equations for the voltage drop across the 5k and 20K.

Then write your KVL equation. Try the outer loop.

Since the current through 20K is 2i, and V1=V3 and V2=V4, the current through 20K can be expressed as (V4-V3)/20K=(V2-V1)/20K=2i

Substitute that back to my node V1: 8i-i=0.004. So i=0.000571429A?
 
  • #6
CWatters said:
First off you can simplify things..

V1 = V3
V2 = V4

Then write equations for the current through the 5k and 20k.

Edit: oh heck I've given you the current through the 20K already. Just write an eqn for the current in the 5k.

Then using those write equations for the voltage drop across the 5k and 20K.

Then write your KVL equation. Try the outer loop.

Got it. Thanks!
 
  • #7
For what it's worth the equation I got was..

(4mA + i1)*5000 - 2i1*20,000 = 0

which can be solved for i1
 
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Related to Help Needed: Solving KCL Equations with Picture Provided

1. What are KCL equations and why are they important?

KCL equations, or Kirchhoff's Current Law equations, are a set of fundamental principles used in circuit analysis to determine the flow of electrical current at a certain point in a circuit. They are important because they allow us to mathematically analyze and understand complex circuits, and are used in a wide range of applications in electrical engineering and physics.

2. How do I solve KCL equations?

To solve KCL equations, you must first draw a circuit diagram and label all the nodes and branches. Then, write out the KCL equations for each node, setting the sum of the currents entering the node equal to the sum of the currents leaving the node. Finally, solve the resulting system of equations using algebraic methods.

3. Can you provide an example of solving KCL equations?

Sure! Let's say we have a simple circuit with three nodes and four branches. We label the nodes A, B, and C, and use Kirchhoff's Current Law to write out the following equations:
Node A: I1 + I2 = I3
Node B: I3 = I4
Node C: I2 + I4 = 0
Solving this system of equations, we can find the values of I1, I2, I3, and I4 in terms of each other.

4. What is the purpose of providing a picture when solving KCL equations?

A picture, or circuit diagram, is essential when solving KCL equations as it helps to visualize the circuit and identify the nodes and branches. It also ensures that the equations are set up correctly and that no nodes or branches have been missed.

5. Are there any common mistakes to watch out for when solving KCL equations?

Yes, some common mistakes when solving KCL equations include forgetting to include all the branches in the circuit, incorrectly labeling the nodes, and making algebraic errors when solving the equations. It is important to double-check your work and ensure that all the equations are set up correctly before solving.

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