Timeline for Finding current using Kirchoff Law, but getting unsolvable system
Current License: CC BY-SA 3.0
9 events
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| Sep 24, 2013 at 7:52 | comment | added | travisbartley | @roverred, At first I tried your equations and was also unable to solve for RREF. I was intrigued by the post so I tried to solve it myself to see if I could remember what I learned in college. I was able to solve by omitting one of the KCL eq and adding one KVL eq, though I don't really know why this is the case. My guess is that you should only have as many KCL eqs as independent nodes - 1. Since each node is defined based on the other nodes, the final node would only give redundant information. | |
| Sep 21, 2013 at 1:00 | comment | added | roverred | Thanks for help guys. It's not for homework, but I was just hoping to improve my understanding of the laws. The book solution uses Delta transforms and it becomes rather easy to solve. @trav1s Regarding having too many KCL equations, how do you know you have too many? I just found out for KVL you should only have as many KVL as independent loops there are. | |
| Sep 20, 2013 at 22:43 | comment | added | helloworld922 | Possibly, the instructions weren't entirely clear because the OP only mentioned Kirchoff's laws, not the actual approach required. MNA uses KCL and ohm's law so as far as I see is just as valid a method as using Mesh Analysis, unless stated otherwise. I've never actually had to solve a problem using KVL and mesh analysis because my professor was opposed to the idea of visualizing current loops and super meshes and I can understand why. | |
| Sep 20, 2013 at 10:24 | comment | added | travisbartley | It seems valid. My concern was if the OP was doing a homework question that needs to be solved a specific way to count. | |
| Sep 20, 2013 at 10:01 | comment | added | helloworld922 | Yeah, I don't reason well with KVL especially as circuits get more complicated. I can see where the extra KCL equation is, but I have to stare really hard at the problem to find which KVL equation is missing. I'll have my MNA any day. | |
| Sep 20, 2013 at 9:58 | history | edited | helloworld922 | CC BY-SA 3.0 |
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| Sep 20, 2013 at 9:48 | history | edited | helloworld922 | CC BY-SA 3.0 |
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| Sep 20, 2013 at 9:47 | comment | added | travisbartley | Wow, +1 for the incredible effort. The circuit was solvable as it was though. You just have to write the right linear equations (the OP had one too many KCL eq and one too few KVL eq), put it in a 6x7 matrix and solve for reduced row-echelon form. | |
| Sep 20, 2013 at 9:42 | history | answered | helloworld922 | CC BY-SA 3.0 |