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

Understanding how to re-draw circuits

  • Engineering
  • Thread starter Lopez
  • Start date
  • #1
8
0

Homework Statement



I need to find I1,I2,I3,Va,Vb but i dont even know to read the circuit. i know how to to do series circuits and parallel circuits but not this. How do i read this circuit and know which ones are in parallel or in series. is there a way to re-draw it? I have the solution and answer. Therefore i dont need the step by step solution since i already have it,is just that it doesnt explain why they did it that why.
These are the I1=4A ,I2=1.33, I3=.67, I4=2.67,va=8.0,and vb i dont know.
Please help understanding what is going on in this circuit.
7.jpeg
 
Last edited:

Answers and Replies

  • #2
Stephen Tashi
Science Advisor
7,023
1,244
If you need a loop, put in a 20 V battery with the positive plate connected to E. Connect the negative plate of the battery to the 3 grounds at the bottom of the diagram.
 
  • #3
33,287
4,990
I would work my way up from the bottom, simplifying bits and pieces as I go. R5 and R3 are in parallel, right? So you could combine those two resistors into a single resistance. Keep chipping away at it until you have a single loop.
 
  • #4
donpacino
Gold Member
1,439
282
If you combine circuit elements you will lose that components individual voltage and/or current.

I reccoend doing a KCL at Va and Va. Then solve for Va and Vb, and the currents will be easy to find.
 
  • #5
8
0
thanks for the tip
 
  • #6
8
0
I would work my way up from the bottom, simplifying bits and pieces as I go. R5 and R3 are in parallel, right? So you could combine those two resistors into a single resistance. Keep chipping away at it until you have a single loop.
if i do ((R5||R3)+R2)||R4 and this would be in series with R1 right? now to get Vb i think i would do Vb=R5(I2-I3) but what if that R5 was not there then how would i solve for vb
 
  • #7
donpacino
Gold Member
1,439
282
if i do ((R5||R3)+R2)||R4 and this would be in series with R1 right? now to get Vb i think i would do Vb=R5(I2-I3) but what if that R5 was not there then how would i solve for vb
If R5 was not there then I2 and I3 would change. you cannot solve for an unknown value with unknown values
 

Related Threads on Understanding how to re-draw circuits

  • Last Post
Replies
6
Views
1K
  • Last Post
Replies
1
Views
988
Replies
6
Views
2K
Replies
9
Views
1K
Replies
3
Views
20K
  • Last Post
Replies
2
Views
5K
Replies
1
Views
5K
Replies
1
Views
1K
Replies
2
Views
780
Replies
15
Views
3K
Top