# Validity of interconnection in electric circuit

Tags:
1. Sep 21, 2016

### Emilio

1. The problem statement, all variables and given/known data

2. Relevant equations
P=Vi

3. The attempt at a solution
For part a, it looks like the dependent current source (4i1) leads directly to i1, with nothing that could change it. This would mean the interconnection is invalid, right? I can't tell if this circuit is in series or in parallel (is it both?), but I know independent voltage sources can't be parallel, and independent current sources can't be in series. I don't know which one would apply here though.

If the circuit is invalid, then I'm not sure how to find the total energy developed, but I guess it would be P=Vi at each node.

#### Attached Files:

• ###### Region.png
File size:
10.7 KB
Views:
43
2. Sep 22, 2016

### Staff: Mentor

There are 2 independent current sources, together pushing how much current downwards to the lower node?

3. Sep 22, 2016

### Emilio

Ah, so they push 240mA towards the lower node, with 4i1 leaving the node. And that would make i1=60mA.

So then lower node = 0 = 180mA+60mA-4i1 = 180mA+60mA-4(60mA), which means it;s valid?

4. Sep 22, 2016

### Staff: Mentor

Next, address the voltage sources. Do they look okay here?

5. Sep 22, 2016

### Emilio

At the top node, according to KVL, the net voltage should be 0=v1+v2. But here, the voltages are in the same direction, and are of different magnitudes so they don't cancel out. Does the dependent current source generate voltage as well? I thought it just changed the current.

6. Sep 22, 2016

### Staff: Mentor

Current sources adjust their terminal voltage to whatever is needed in order to force their designated current through the circuit.