Nodal Analysis Question

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Juice_brabus

Joined May 19, 2020
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H,i i need to complete this circuit finding the voltage, current and power dissipated across the 9/18 ohm resisters. I'm assuming i need to use nodal analysis but I'm not sure, and if i am how would i find the current across the blank top-middle wire for each equation?
 

WBahn

Joined Mar 31, 2012
25,785
Unless you are told otherwise, you can use any analysis technique you like. In this case, superposition makes it trivially easy. Even easier is to recognize that the two current sources are effectively in parallel. With that, and with the concept of current division across two resistors in mind, you can get the currents in the two resistors of interest by inspection (I'll give you a ballpark number -- one of the resistors has about 1.5 A flowing in it).

As for the current in the bridging wire, if you use mesh analysis you've have that directly. Otherwise, once you know the currents in the two resistors of interest you can just apply KCL to that top either of the junctions on the top node (I'd apply it to both to verify that the answers agree).
 

MrAl

Joined Jun 17, 2014
7,604
View attachment 207579
H,i i need to complete this circuit finding the voltage, current and power dissipated across the 9/18 ohm resisters. I'm assuming i need to use nodal analysis but I'm not sure, and if i am how would i find the current across the blank top-middle wire for each equation?
Basic Nodal Analysis starts from noting that the difference in voltage across a resistor is related to the current though it:
I=(v1-v2)/R

Also a hint: the two middle resistors are in parallel so they can be reduced to one resistor.
 
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