Hi I need some help trying to solve IO in this mesh current analysis problem. Element E is a 5 volt power supply with the + at the top. What I originally did....

Set mesh 1 (ia) in the left loop as

10=5000ia-10000ia+10000ib

and mesh 2 (ib) in the right loop as

5=10000ia-10000ib-4000ib

after algebraic manipulation I found ia=.004167a and ib=.006333. Then I subtracted ia from ib and thought io=-.002167. However, the book's answer was -.136ma. Please help!

 

Your equation is wrong man. It's must be :
15000Ia - 10000Ib = 10
-10000Ia + 14000Ib = 5

Calcultes it then substracts you will get the right answer -136mA

 

Try read this
http://www.allaboutcircuits.com/vol_1/chpt_10/3.html

 

hmmmm I understand how mesh b is -10000Ia + 14000Ib = 5, but I'm puzzled about how mesh a is 15000Ia - 10000Ib = 10. Isn't the it -5000ia+10+10(ia-ib)?

 

I like to write it in this way
-10 - 10000 (Ia - Ib) - 5000 Ia = 0
-4000Ib - 5 - (Ib - Ia) 10000 = 0

Io = - 3/22000 = 136.363636uA

 

Hmmm. I'm sorry if I'm still asking questions about this problem, but I want to fully understand this method.

From what I read, I thought that traversing the loop should be in a clockwise direction, so I thought that it would be -5kia since it's going negative to positive, then 10v since it's going positive to negative then positive 10k(ia-ib) since it's going positive to negative.

 

Read the link I post
"The choice of each current's direction is entirely arbitrary"

 

OOO! I see now. Thank you everyone!