# Kirchhoff's voltage law problem: Batteries, switches, resistors

• kenok1216
In summary, the conversation discusses finding the current in each resistor for a circuit with four closed switches. The solution to the problem involves solving three equations for the three different currents in the circuit. The reason for having three currents is because they are measured through wires, not in loops, and the currents going out from the top two wires return in the third wire.
kenok1216

## Homework Statement

for S1,S2,S3,S4 are all closed at the long time
find the current in each resistor

## The Attempt at a Solution

why I3 is not = i2?
the solution of this question is
24-28I1-I212-12=0
7I1-32=3-----(1)

12-12I2-163=0
3I2+43=3 ---(2)

I1+I2-I3=0---(3)

I1=0.492 I2=0.148 I3=0.639[/B]
why there are 3 current in 2loop and I2 is not =I3 and why at the top loop
the equation is not 24-28I1-[I1-I2]12-12=0?

kenok1216 said:
why there are 3 current in 2loop
Currents are measured through wires, not in loops. There are three wires through which different currents are flowing (ignoring the wires with negligible resistance), so we measure three currents.
and I2 is not =I3
Because the currents going out rightwards from the top two wires return leftwards in the third wire.

andrewkirk said:
Currents are measured through wires, not in loops. There are three wires through which different currents are flowing (ignoring the wires with negligible resistance), so we measure three currents.
Because the currents going out rightwards from the top two wires return leftwards in the third wire.
Thank

## 1. What is Kirchhoff's voltage law?

Kirchhoff's voltage law, also known as Kirchhoff's second law, states that the sum of all voltage drops in a closed loop circuit must equal the sum of all voltage sources in that same loop. This law is based on the principle of conservation of energy.

## 2. How do batteries, switches, and resistors relate to Kirchhoff's voltage law?

In a circuit, batteries provide a constant voltage source, switches allow for control of the flow of current, and resistors create a drop in voltage. All of these components play a role in following Kirchhoff's voltage law.

## 3. What is a common problem encountered when applying Kirchhoff's voltage law?

A common problem encountered when applying Kirchhoff's voltage law is the presence of multiple loops in a circuit. This can make it difficult to accurately determine the voltage drops and sources in each loop.

## 4. How do you solve a Kirchhoff's voltage law problem?

To solve a Kirchhoff's voltage law problem, you must first label the voltage sources and resistors in the circuit. Then, you can use Kirchhoff's voltage law to write equations for each loop in the circuit. Finally, you can solve the equations simultaneously to find the voltage drops and sources in each loop.

## 5. Can Kirchhoff's voltage law be applied to any type of circuit?

Yes, Kirchhoff's voltage law can be applied to any type of circuit, including series and parallel circuits. It is a fundamental law in circuit analysis and is essential for understanding the behavior of electrical circuits.

• Introductory Physics Homework Help
Replies
1
Views
830
• Introductory Physics Homework Help
Replies
16
Views
1K
• Introductory Physics Homework Help
Replies
22
Views
3K
• Introductory Physics Homework Help
Replies
12
Views
1K
• Introductory Physics Homework Help
Replies
18
Views
2K
• Introductory Physics Homework Help
Replies
1
Views
1K
• Introductory Physics Homework Help
Replies
6
Views
2K
• Introductory Physics Homework Help
Replies
3
Views
3K
• Introductory Physics Homework Help
Replies
4
Views
3K
• Introductory Physics Homework Help
Replies
2
Views
1K