What is the voltage in the circuit?

In summary, the conversation was about a problem involving loop analysis and nodal equations in circuit analysis. The original poster had a question about their solution and another user pointed out a mistake in their nodal equation. The original poster then corrected their mistake and both users arrived at the same answer of 13.12 V. The conversation also included a request for help on another problem using loop analysis.
  • #1
ee_ess_ee-kid
15
0

Homework Statement



http://i.imgur.com/YRK5L.png

Homework Equations



Loop analysis, so KVL

The Attempt at a Solution



I did the problem, and I got V0 = 12.5292V. If this is incorrect, I'll be more than happy to upload my work. Can someone verify the answer for me? Just tell me if it's right or wrong.
 
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  • #2
I got Vo+ - Vo- = +14.359 V.

I use nodal equations rather than loop equations. I've always thought loop equations were stupid. I just pick every independent node and sum currents = 0. For example, my first (of three) equation is

(10 - Vx)/2K + (Vo+ - Vx)/3K + 8mA = 0.
Vx is the voltage in the middle. I made the bottom node zero V. (I really should have made Vo- = 0 but it doesn't matter).

I don't want to look at your loop equations, for which I apologize. I just don't like it when one component can carry 2 or 3 or even more "currents"!

BTW I used math app software to do the equation solving so my answer is correct assuming I wrote the equations right. I checked carefully but they could still be wrong, of course.
 
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  • #3
It seems like your example nodal equation is for the middle node, in which case, I think it looks incorrect?

If it is the middle node, you forgot to consider the 2k resistor to the right of the node.
 
  • #4
You are absolutely right!

I will recompute. Thanks for bringiong that to my attention.
 
  • #5
Now I get +13.12V.

Here are my three equations, maybe you can spot another mistake. Don't be confused by the fact that I use conductances instead of resistances: G = 1/R. It makes the math easier for me. Conductances are in mS, currents in mA (1mS = 1/1K ohm):

0.5(10-x) + .33333(Vop-x) + 8 + 0.5(Von-x) = 0
4 = 0.33333(Vop-x) + 0.125(Vop-Von)
0.125(Vop-Von) + 0.5(x-Von) = 0.125Von
 
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  • #6
rude man said:
Now I get +13.12V.

Here are my three equations, maybe you can spot another mistake. Don't be confused by the fact that I use conductances instead of resistances: G = 1/R. It makes the math easier for me. Conductances are in mS, currents in mA (1mS = 1/1K ohm):

0.5(10-x) + .33333(Vop-x) + 8 + 0.5(Von-x) = 0
4 = 0.33333(Vop-x) + 0.125(Vop-Von)
0.125(Vop-Von) + 0.5(x-Von) = 0.125Von

Awesome, I tried doing the problem again and it seemed like I missed something in my loop equations as well. I got 13.12 V too.
 
  • #8
Could you possibly look at my other question please?

https://www.physicsforums.com/showthread.php?t=539166"

It uses loop analysis, which I know you said earlier that you dislike, but primarily I'd like to know if my answer is correct. Thanks.

In the best case scenario, you could maybe point out my error in my work. I put all of my equations in the post. Thanks again for your help on this problem!
 
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FAQ: What is the voltage in the circuit?

How do I find the voltage in a circuit?

The voltage in a circuit can be found by using Ohm's Law, which states that voltage (V) is equal to the current (I) multiplied by the resistance (R). In other words, V = I x R.

What tools do I need to find the voltage in a circuit?

You will need a multimeter, which is a device that measures voltage, current, and resistance. It is important to use a multimeter with the correct range for the voltage you are trying to measure.

3. Can I find the voltage in a circuit without a multimeter?

Yes, you can use a voltmeter or a voltage probe to measure the voltage in a circuit. These tools are specifically designed for measuring voltage and can give you an accurate reading without the need for a multimeter.

4. What is the unit of measurement for voltage?

The unit of measurement for voltage is volts (V). It is a measure of the electric potential difference between two points in a circuit.

5. What factors can affect the voltage in a circuit?

The voltage in a circuit can be affected by the power source, the components in the circuit, and the resistance of the circuit. Changes in any of these factors can cause the voltage to increase or decrease.

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