# Fundamentals of Electric Circuits - Sadiku Question on KVL

• Engineering
• Paola Flores
In summary, the conversation discusses a question about the application of KVL in a circuit problem. The individual is confused about the signs used in the equations and is seeking clarification on why the current direction is opposite to what they expected. They are hesitant to ask their teacher and are hoping for an explanation from other students. The conversation also mentions that the current direction is defined as going to the left and this directly affects the sign in the equation.
Paola Flores
Member advised to use the formatting template for all homework help requests

Hi, this is my first time posting, I'm glad there is a space like this where we can share our doubts and hopefully get some help from other students.

As you can see on the image above, there's a KVL applied to the circuit in practice problem 2.6, but my question is the following:
On equation 2.6.1:

-12+4i+2v0-4+6i=0

for resistance V0, isn't that supposed to be -6i due to direction of the current?, a resistance can only dissipate which would make obvious the + but even on 2.6.2 it states V0=-6i, I don't want to ask my teacher because I feel the answer is probably something obvious that I am probably missing. Can anyone please elaborate on why this is being added instead of substracted to the KVL?

Thank you so much!

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• practice_problem_2_6.jpg
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The entire 2.6.1 has the opposite sign of what I would have used, but it is consistent. Note that the current i goes to the left in the lower line.

Paola Flores said:
but even on 2.6.2 it states V0=-6i
This has to do with the definition of ##v_0## with the higher potential being to the left and the current being defined as going to the left. This equation tells you directly that the current is going in the opposite direction of what was used in the KVL loop.

Paola Flores

## 1. What is KVL and why is it important in electric circuits?

KVL stands for Kirchhoff's Voltage Law and it is a fundamental law in electric circuits. It states that the sum of all voltages around a closed loop in a circuit must equal zero. This is important because it helps us analyze and understand the behavior of electric circuits, and allows us to make accurate calculations and predictions.

## 2. How do we apply KVL in solving problems in electric circuits?

To apply KVL, we first identify all the closed loops in the circuit. Then, we assign a direction to each loop and label the voltage drop across each component in that direction. Using the KVL equation, we set the sum of all voltage drops equal to zero and solve for any unknown voltages. This process helps us determine the voltage distribution in a circuit, which is crucial in circuit analysis.

## 3. Can KVL be applied to any type of circuit?

Yes, KVL can be applied to any type of circuit, regardless of its complexity. It is a fundamental law that holds true for all circuits, whether they are series, parallel, or a combination of both. However, KVL may not be applicable in certain cases, such as circuits with non-ideal components or those operating at high frequencies.

## 4. What are some common misconceptions about KVL?

One common misconception about KVL is that it only applies to simple, linear circuits. In reality, KVL is a fundamental law that can be applied to any type of circuit, including non-linear and complex circuits. Another misconception is that the voltage drop across a resistor is always equal to the voltage source connected to it. In some cases, the voltage drop may be less than the source due to internal resistance or other factors.

## 5. How does KVL relate to other laws and principles in electric circuits?

KVL is closely related to other fundamental laws and principles in electric circuits. It is often used in conjunction with Kirchhoff's Current Law (KCL), which states that the sum of all currents entering and leaving a node in a circuit must equal zero. KVL can also be used in combination with Ohm's Law to analyze and solve problems in electric circuits.

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