Use node voltage method to solve i2 vbe and vce

In summary, the problem is that the user wants to solve for I0 and V0 using voltage division. However, they have to include the two series resistors in order to get the first voltage divider resistors. Once they have this first voltage divider, they can work out the voltages and currents across the rest of the resistors in parallel.
  • #1
Ninja_IPGO
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0
I have attached the problem and the worked out solution can a few people go over it and post if it's right and if not what is wrong with it.

Using node voltage method
 

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  • #2
Hey man i am not sure where you went wrong in your work but it isn't correct. I would first combine all those resistors that are in parallel to get an Req of 5000/17 ohms. Then the problem is really easy to set up. Then to split them back you will need to use current or voltage division to find the proper current through or voltage drop of the resistors. (Parallel resistors have the same voltage across them), hope that helps.
 
  • #3
the problem is he wants me to solve it using node voltage analysis I am going through some class notes now and i'll post a new version later on tonight I ll see what i can do with the information you gave me thank you
 
  • #4
I get 263 ohms for the parallel combination.

You can work out the voltages and currents with just a calculator and then at least you will know if what you are getting makes sense when you do the node analysis.

I would add a LOT more explanation and diagrams. I couldn't see where most of that was coming from and I shouldn't have to be guessing.

Draw the part of the diagram you are dealing with and justify each step before you go on.
 
  • #5
Interesting vk6kro because:

[tex] R_{eq}^{-1} = 2500^{-1} +500^{-1}+1000^{-1} =.0034 [/tex]

and

[tex] .0034^{-1}=294.1176471=\frac{5000}{17} [/tex]

how'd you get 263?

@Ninja IPGO, I am currently taking electrical fundamentals for the first time (i don't know what class you are taking but it looks much the same) and we can use any 'tools' we have to solve any of the problems. Why would there be a problem combining resistors in this problem? It is what you would do in a similar real life situation.

edit: what i really meant is if the problem says 'use mesh analysis to solve for i0 an v0' we could most certainly combine resistors to solve the problem, just not use node voltage. I don't see using voltage, current division or series/parallel combination as 'not using the method specified'.
 
  • #6
You have in parallel:

(1500 + 1000), 2500, 500, 1000 ohms

And this gives 263.158 ohms.

You put this in series with the 750 ohms across 100 volts to get the voltage at node b.

Then you have 2500 ohms in series with 1000 ohms across this voltage to get the voltage at node c.
 
  • #7
oh i see, i was just combining the 2.5k 500 and 1k resistors, to combine the rest does not seem to be a productive way to getting to the end quickly
 
  • #8
But, you have to include the two series resistors to get the first voltage divider resistors.

You have 750 ohms then in series with 263 ohms across 100 volts. It is easy to work out the voltage across the 263 ohms. (100 times 263/1013)

Now that you know this voltage, it is across all the resistors in parallel including the two that are in series with each other.
So, they form a new divider and you can work out the voltage across the 1000 ohm resistor.
(100 times 263/1013) times 1000/2500.

It is so easy, you just write down the answers off the calculator.
 
  • #9
While your method is not wrong i maintain mine is much quicker and more efficient. I did a schematic in LTspice of this circuit and using my method works just fine. No need to combine them all man.
 
  • #10
i redid the problem there was a few algebraic errors but the method i used is correct
 

What is the Node Voltage Method?

The Node Voltage Method is a technique used to analyze and solve electrical circuits by determining the voltage at each node in the circuit. It involves creating equations based on Kirchhoff's Current Law and Ohm's Law to solve for the unknown node voltages.

How do you use the Node Voltage Method to solve for i2?

To solve for i2 using the Node Voltage Method, you first need to identify the node where i2 passes through. Then, you can use Kirchhoff's Current Law to create an equation based on the currents entering and leaving the node. Finally, you can solve for i2 by setting the equation equal to 0 and solving for the unknown current.

How do you use the Node Voltage Method to solve for vbe?

To solve for vbe using the Node Voltage Method, you first need to identify the nodes where vbe is present. Then, you can create an equation based on the voltage drops across the elements in the circuit using Ohm's Law. Finally, you can solve for vbe by setting the equation equal to the known voltage and solving for the unknown voltage.

How do you use the Node Voltage Method to solve for vce?

To solve for vce using the Node Voltage Method, you first need to identify the nodes where vce is present. Then, you can create an equation based on the voltage drops across the elements in the circuit using Ohm's Law. Finally, you can solve for vce by setting the equation equal to the known voltage and solving for the unknown voltage.

What are the advantages of using the Node Voltage Method?

There are several advantages to using the Node Voltage Method. It is a systematic and organized approach to solving circuits, making it easier to keep track of equations and variables. It also allows for the analysis of complex circuits with multiple voltage sources and resistors. Additionally, the method can be used to solve for any unknown voltage or current in the circuit.

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