Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
TomLikesPhysics
Group Title
I am supposed to take a hard look at this network, come up with a matrix and use it to get all the currents. Can someone help me to setup the equations for the matrix?
 one year ago
 one year ago
TomLikesPhysics Group Title
I am supposed to take a hard look at this network, come up with a matrix and use it to get all the currents. Can someone help me to setup the equations for the matrix?
 one year ago
 one year ago

This Question is Closed

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
This is what I came up with. But according to Wolfram Alpha it can not be solved so I guess my equations to begin with a wrong.
 one year ago

BluFoot Group TitleBest ResponseYou've already chosen the best response.0
Can you rotate the picture please? My neck kinda hurts otherwise :P
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
o.O Seriously? Every picture is oriented in the right way.
 one year ago

BluFoot Group TitleBest ResponseYou've already chosen the best response.0
Oh, I'm new sorry. That's a stupid interface. OK I downloaded it... Do you know what A and B are supposed to stand for? voltage sources I guess?
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
Between A and B we got 10 Volts.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
If you set it up using mesh analysis you find that you have two equations and two unknowns. Start with the left mesh and you get: \[R_1i_1 + R_5(i_1i_2) + R_2i_1 = 0\] and for the right: \[R_4i_2 + R_5(i_2i_1) + R_3i_2 = 0\] Build your matrix from that.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
:O I thought I have 56 unknows and as much equations. You did not consider the currents that run into a knot.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
Why don´t you got a i4 and i3?
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
Because there are only two meshes (loops).
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
Maybe this will help: http://www.allaboutcircuits.com/vol_1/chpt_10/3.html
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
Yes but that does not mean that the current that runs through r2 is also the current that runs through r4.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
Well no, because a mesh is voltage, r*i, so you know the voltage on each of them and thus you can calculate the current through each element.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
But we also do not know the voltage on r2 and r4 so we can not say if there runs the same current or not. Why don´t you consider also looking at the knots?
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
A place where the current that goes in equals the current that goes out. The other important part of kirchoffsrule. Perhaps node is the right word?
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
The thick dots on the drawing where one line splits into two lines.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
Ah, nodes. The nodes are considered. But you know that the voltage drops around any loop equal zero. If you want to do node analysis you would need to know a little more information like the voltage on each side of your circuit or maybe one of the drops within it.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
I know the voltage between A and B is 10 Volts.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
And through Kirchhoff I know that the currents in a node add up to zero. I used three nodes and two mashes to get five equations. You can see them in the top.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
Well you only have two nodes where two or more components meet so that would only yield one equation. Kirchoff's current law says that the current entering a node must equal the current leaving the node, so they do not equal zero.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
There are four nodes.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
I meant to say, three or more components meet.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
However to use node voltage method, you need a reference node as well.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
Well know that all the current that goes in has to come out.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
What do you mean with reference node?
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
One that equals zero. Although if you took your 'A' side and called it 0, your 'B' as +10, you could do a node equation for the top, and bot nodes. That would give you four equations and four unknowns I believe.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
Including the mesh equations.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
But if you sum up all the currents equal zero for any node. I don´t need a reference node. Otherwise it would mean that there are electrons pilling up in the node if the sum of all the currents entering and exiting the node does not equal zero.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
Perhaps the analysis you are tasked with is using a method that I am unfamiliar with. I am not sure who would be a good person to ask though.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
I think I just have to use all of Kirchhoffsrules.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
You are going to have 7 unknowns using KCL, with the information you are given it seems to me that using mesh and node analysis would be the easiest way to approach this.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
Why do you get 7 unknowns? I get max. 6. We can conclude that I that comes from A into the network is the same I that goes out of the network into B.
 one year ago

eSpeX Group TitleBest ResponseYou've already chosen the best response.2
Accounting for all of the currents I get 7, if you wish to discount your ib=ia then you would have 6, yes.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
Did you solve the system? I threw mine into Wolfram Alpha and got weird stuff, for example i1=i2. That seems very weird to me. Also i4 and i5 are booth negative.
 one year ago

TomLikesPhysics Group TitleBest ResponseYou've already chosen the best response.0
Can you perhaps help me to calculate the total resistance of this network?
 one year ago

phi Group TitleBest ResponseYou've already chosen the best response.0
Here is how Prof. Strang would do the problem http://ocw.mit.edu/courses/mathematics/18085computationalscienceandengineeringifall2008/videolectures/lecture12graphsandnetworks/ I thought I would apply his approach to your problem.
 one year ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.