Why is Vi - Vf used to calculate voltage in circuits?

In summary, the conversation discusses the calculation of voltage across a circuit element and the use of vi - vf instead of vf - vi. The speaker suggests that this may be due to calculating the potential energy drops/gains of the circuit element rather than the current. The book being read does not provide an explanation for this calculation method. The conversation also mentions the Kirchhoff's voltage law and provides an example using a battery and resistors.
  • #1
Miike012
1,009
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My question is why did they choose to calculate the voltage across a circuit element as vi - vf because it seems contradictory.
More detail is in the document.

Someone please answer because this has been bothering me.
THank you.
 

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  • #2
My guess is that instead of calculating the potential energy drops/gains of current they are calculating the potential energy drops/gains of the circuit elements which is the negative of the potential energy drops/gains of current. It's just frustrating because the book doesn't explain why they are doing what they are doing. Are there any first semester circuits books that give explanations? The book I am reading from is
https://www.amazon.com/dp/0470633220/?tag=pfamazon01-20
 
  • #3
If you use Vi-Vf then you would change the signs. Vi -Vf = -(Vf-Vi). When you calculated it you used Vf-Vi.

BTW, Vr1 + Vr2 - M = 0.

When you start at the bottom, you first go into the - side of the battery, and then into the + side of two resistors.

Read the wikipedia page on kirchhoffs voltage law.
 

1. What is an introductory circuits problem?

An introductory circuits problem is a type of problem commonly encountered in the study of electrical circuits. It typically involves using basic circuit laws and principles to analyze and solve a given circuit, which may involve resistors, capacitors, inductors, and other components.

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The best way to approach solving an introductory circuits problem is to break it down into smaller, more manageable steps. Start by identifying the known values and variables in the circuit, then apply the relevant circuit laws and principles to find the unknown values. It can also be helpful to draw a circuit diagram and use equations and diagrams to visualize the problem.

3. What are some common challenges in solving introductory circuits problems?

Some common challenges in solving introductory circuits problems include understanding and applying the various circuit laws and principles, as well as interpreting circuit diagrams accurately. Additionally, complex circuits with multiple components or sources can be more difficult to analyze and solve.

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Introductory circuits problems are used in a wide range of real-world applications, including designing and troubleshooting electronic circuits, analyzing power distribution systems, and developing renewable energy sources. They are also essential for engineers and scientists working in fields such as electrical engineering, physics, and computer science.

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