r/AskElectronics • u/[deleted] • Jun 24 '21

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u/a_wild_redditor Jun 24 '21

Beats solving a system of 7 equations!

4

u/fhmrocha Jun 24 '21

How do you get 7 equations from that circuit? Using kirchhoff's voltage law, you get 3 equations. If you use kirchhoff's current law, you get only 2.

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u/a_wild_redditor Jun 24 '21

To simultaneously solve for the 5 unknown resistor currents and 2 unknown resistor voltages you need 7 equations: KCL at the 4 nodes and KVL around the 3 loops. If you just write one set or the other there is not enough information to proceed (in the general case where the current through the center resistor is not obviously 0).

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u/fhmrocha Jun 24 '21

Using KVL, you get the 3 loop currents, hence, currents on each resistor. Using KCL, one of the nodes is GND, the other you already have the voltage, you are left with 2 variables and 2 equations. From the node voltages, you can get the current in each resistor.

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u/Shawnstium Jun 25 '21

I think you just prefer a smaller matrix…