• Support PF! Buy your school textbooks, materials and every day products Here!

Parallel voltage sources circuit

  • #101
I like Serena
Homework Helper
6,575
176
So now I want to find Vcd

So!

Vc -> 0

(I can do that, right? Set Vc as my zero point, since it makes things easier)


Vcd = I2 x 0.5 - I3 x 4 = 8.615 x 0.5 - 2.077 x 4 = -4 V

Yes? :smile:
Wow! You're starting to make up your own exercises! Cool! :cool:

Well, let's see....
You followed the wire down and back up.

Can you also follow the wire up and then back down?

(As for setting Vc to zero. I guess that's fine, although I wouldn't write it down.)
 
  • #102
Femme_physics
Gold Member
2,547
1
Wow! You're starting to make up your own exercises! Cool!

Well, let's see....
You followed the wire down and back up.

Can you also follow the wire up and then back down?
Vcd = 6 - 10 = -4V


w00t :D

(As for setting Vc to zero. I guess that's fine, although I wouldn't write it down.)
Why wouldn't you?
 
  • #103
I like Serena
Homework Helper
6,575
176
Why wouldn't you?
Well, suppose you set Vc to zero because you want to calculate Vcd.

And then you set Va to zero because you want to calculate Vab.

But now... you have set both Va and Vc to zero, which can't both be true!


You can use it as a trick in your mind to find Vcd, but Vc does not really have to be 0 [V].
Especially not if there is a ground attached to some other point of the circuit.
 
  • #104
Femme_physics
Gold Member
2,547
1
Well, suppose you set Vc to zero because you want to calculate Vcd.

And then you set Va to zero because you want to calculate Vab.

But now... you have set both Va and Vc to zero, which can't both be true!
Well I don't have to use the fact that Vc = 0 anymore when I look for ab.

I can write IF Vc = 0 then Vcd equals...

And then at the other clause I write

IF Va = 0 then Vab equals....


Especially not if there is a ground attached to some other point of the circuit.
If there is a ground, I have to use the ground they give me, right? As of now, it's kind of a groundless circuit
 
  • #105
I like Serena
Homework Helper
6,575
176
Well I don't have to use the fact that Vc = 0 anymore when I look for ab.

I can write IF Vc = 0 then Vcd equals...

And then at the other clause I write

IF Va = 0 then Vab equals....
The problem with those statements is, that Vcd will still equal whatever you calculated, even if Vc is not zero (since Vcd is a "difference").



If there is a ground, I have to use the ground they give me, right? As of now, it's kind of a groundless circuit
Yes. It's groundless.
 
  • #106
Femme_physics
Gold Member
2,547
1
Yes. It's groundless.
Is this like our "circuit flowing in space" idea? Not connected to ANYTHING!

The problem with those statements is, that Vcd will still equal whatever you calculated, even if Vc is not zero (since Vcd is a "difference").
So in other words I don't have to define anything as my "zero" point. :smile: Duly noted!
 

Related Threads for: Parallel voltage sources circuit

  • Last Post
Replies
10
Views
2K
  • Last Post
Replies
24
Views
3K
  • Last Post
Replies
1
Views
1K
Replies
2
Views
370
Replies
5
Views
2K
Replies
20
Views
3K
Replies
2
Views
1K
Top