Find Vc(0): Node Analysis & Ohms Law

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Discussion Overview

The discussion revolves around finding the voltage Vc(0) using node analysis and Ohm's law. Participants are engaged in a homework problem that involves circuit analysis, specifically focusing on expressing voltages and currents in terms of each other within a schematic.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant expresses difficulty in finding Vc(0) and seeks suggestions after attempting node analysis.
  • Another participant suggests replacing Vo with another expression derived from the schematic, prompting further exploration of relationships between circuit quantities.
  • There is a question about whether Vo can be expressed as (V-10)/25, which is clarified to be incorrect due to the order of operations and the nature of the branch current.
  • A participant proposes that the current can be expressed as i = Vo/20, which is acknowledged as a valid approach.
  • Further discussion leads to a suggestion of calculating the current as i=10/25 = 0.4A to find Vo, but this is challenged based on the placement of the battery voltage in the circuit.
  • Participants are encouraged to derive expressions for branch currents and voltages based on their earlier equations and assumptions.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct expressions for Vo and the branch current, indicating ongoing uncertainty and exploration of different approaches.

Contextual Notes

Limitations include potential misunderstandings of circuit relationships, order of operations in mathematical expressions, and the specific placement of voltage sources in the schematic, which may affect the derived equations.

sammyqw
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Homework Statement


find Vc(0)

Homework Equations


Node analysis , ohms law

The Attempt at a Solution


image.png

Hi, I'm trying to find Vc(0). I used node analysis but I'm stuck in eq 1. I'll appreciate if someone can give me some suggestions. Thanks
 
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Looks like you need to replace Vo with something. Go back to your schematic and see if you can express Vo in terms of the other quantities pertaining to the branch it's in.
 
gneill said:
Looks like you need to replace Vo with something. Go back to your schematic and see if you can express Vo in terms of the other quantities pertaining to the branch it's in.
Can I replace Vo with V-10/25 ?
 
sammyqw said:
Can I replace Vo with V-10/25 ?
Do you mean (V-10)/25? (Order of operations is important). No, that would be the branch current flowing from v towards the 10 V source. But that's a start. What would be Vo in terms of that current?
 
gneill said:
Do you mean (V-10)/25? (Order of operations is important). No, that would be the branch current flowing from v towards the 10 V source. But that's a start. What would be Vo in terms of that current?
it would be some current i = Vo/20 ?
 
sammyqw said:
it would be some current i = Vo/20 ?
That's the idea. But you've already identified the branch current in post #3.
 
gneill said:
That's the idea. But you've already identified the branch current in post #3.
Can I do i=10/25 = 0.4A then find Vo= (0.4)20 =8V and then just replace it in my equation 2?
 
sammyqw said:
Can I do i=10/25 = 0.4A then find Vo= (0.4)20 =8V and then just replace it in my equation 2?
No because the battery voltage is not across the branch. What is an expression for the branch current (you wrote one as a term in your node equation!)?
 

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