# Understanding how to re-draw circuits

• Engineering

## 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. Last edited:

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Stephen Tashi
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.

• Lopez
Mark44
Mentor
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.

• Lopez
donpacino
Gold Member
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.

thanks for the tip

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

donpacino
Gold Member
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