Engineering Struggling with Nodal Analysis and Voltage Calculations

AI Thread Summary
The discussion centers on discrepancies between nodal analysis and loop analysis in a circuit problem involving resistors and capacitors. The user calculates a node voltage of nearly 15 V using nodal analysis, assuming capacitors are open circuits, but finds different results when applying loop analysis. The loop analysis yields a current of 0.5 mA, leading to different voltage calculations for V1, V2, V3, and V4. The confusion arises from an arithmetic mistake in the nodal analysis calculations, which affects the voltage results. Clarifying the calculations and ensuring accuracy in the nodal analysis will resolve the inconsistencies.
gfd43tg
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I am having a little issue with this problem, because when I do nodal analysis, I get the voltage of the node above the 5 kΩ resistor to be nearly 15 V. I am assuming all of the capacitors are saturated, and therefore act as open circuits. That means no current goes through the 20k or 30k resistors, and therefore the voltage v2 and v1 should be the same as the voltage V, almost 15 V.

However, then I try a different approach and do a loop around the 5k, 15k, and 10k resistors, knowing all other wires lead to an open circuit. I get a current of 0.5 mA. Then to find v3, knowings its in parallel with the 15k resistor, I do the current times 15k to get the voltage, and similarly with the 10k and v4.

for v1 and v2, I do 15V - 5000(0.5x10^-3) = 12.5 V, which does not agree with my nodal analysis. What is going on here??
 

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V2 and V1 would equal V iff there were zero current through the 5k resistor.

Your calculations for V1, V3 and V4 are correct, the loop current is 0.5mA
 
Why is my nodal analysis revealing something different? Also, is my V2 correct?
 
Maylis said:
Why is my nodal analysis revealing something different? Also, is my V2 correct?
You have made an arithmetic blunder in calculating V.
 

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