Should Vout be negative or positive?

In summary, the conversation is about analyzing a circuit using Kirchhoff's voltage law to find the output voltage. The current is assumed to go clockwise and is found to be -2*10^-4 A. Using this value, the output voltage is calculated to be -8V. The speaker notes that the output voltage should be negative based on the polarity of the voltage sources. The other speaker confirms this and explains that the top of the voltage sources will be negative compared to the bottom. They also mention the importance of drawing voltage and current arrows when analyzing a circuit. The first speaker then asks if the problem was solved and the other speaker responds that they can tell just by looking at it that the output voltage will be negative.
  • #1
Clandry
74
0
I attached the circuit.

I did kirkoff's voltage law (assuming current goes clockwise):
-15+5-10,000I-40000I=0 where I=current
I=-2*10^-4 A

V_out=40,000*-2*10^-4A = -8V
The way V_out is shown, it should solve to be negative, correct?
 

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  • #2
Clandry said:
The way V_out is shown, it should solve to be negative, correct?

Correct.
 
  • #3
V is the difference betwen potentials at two places in the circuit.
If you look at the voltage sources, the top is less positive than the bottom - so the bottom must have a higher potential than the top. Replace the voltage sources with an equivalent single voltage source and the answer to your question will become clear.

Note: when you do kirkoffs laws to analyze a circuit - draw voltage arrows on the components as well as current arrows at the nodes.
 
  • #4
gneill said:
Correct.
Did you solve the problem?
I'm asking because if you didn't, can you tell just by looking it that it will be negative?
 
  • #5
Clandry said:
Did you solve the problem?
I'm asking because if you didn't, can you tell just by looking it that it will be negative?

Yes, I can tell just by looking; But I've looked at a LOT of circuit problems over the years!

I took note of the two voltage supplies and determined that the top of them will be negative w.r.t. the bottom. I then looked at the polarity specified for "measuring" the output and drew the conclusion that Vout must be negative.
 

1. Should Vout be negative or positive?

The answer to this question depends on the specific circuit and its intended purpose. In some cases, a negative Vout may be desired to achieve certain functions or to match the input signal. In other cases, a positive Vout may be more appropriate. It is important to carefully consider the circuit design and its requirements before determining whether Vout should be negative or positive.

2. How does Vout affect circuit performance?

Vout, or the output voltage, can have a significant impact on the performance of a circuit. It can affect the overall gain, frequency response, and stability of the circuit. Therefore, it is important to carefully consider the value and polarity of Vout when designing a circuit.

3. What factors determine whether Vout should be negative or positive?

There are several factors that can influence whether Vout should be negative or positive. These include the input signal, the desired output signal, the components used in the circuit, and the intended function of the circuit. It is important to carefully analyze these factors to determine the appropriate polarity for Vout.

4. Can Vout be both negative and positive?

In some cases, Vout may need to alternate between negative and positive values. This is often seen in circuits that use AC signals. In these cases, the polarity of Vout will depend on the phase of the input signal and the specific components used in the circuit.

5. How can I determine the appropriate polarity for Vout in my circuit?

Determining the appropriate polarity for Vout requires careful analysis and understanding of the circuit design. It is important to consider the input signal, the desired output signal, and the components used in the circuit. Additionally, simulations and calculations can be performed to determine the best polarity for Vout in a given circuit.

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