Calculate Voltage: R1-R6, I4 = 4A

[stefanomm]

Homework Statement

R1=30Ω R2=20Ω R3=20Ω R4=10Ω R5=40Ω R6=10Ω I4=4A
I need to calculate U (total voltage)
schematic:
http://i43.tinypic.com/2jvbx2.png

Homework Equations

The Attempt at a Solution

R23=1/(1/10+1/20)=10ohm
R234=10+10=20ohm
R2345=1/(1/R234+1/R5)=1/(1/20+1/40)=13,33ohm
Rv=R1+R2345+R6=30+13.33+10=53,33ohm
U=I4*Rv=4*53.33=213,33V

213,33V is not correct...

 

[tiny-tim]

Welcome to PF!

Hi stefanomm! Welcome to PF!

(try using the X₂ tag just above the Reply box )

U=I4*Rv=4*53.33=213,33V

No, I₄ is the current through R₄ only …

you need to find the "overall" current

(call it I, and find the relation between I and I₄).