Using Kirchhoff's Laws to find current in a circuit

In summary, the conversation is about finding the values of I1, I2, and I3 in a circuit using Kirchhoff's Voltage and Junction Laws. The equations for the left and right loops are provided and the person is struggling to solve the system of equations. They are seeking help in the "introductory Physics" forum.
  • #1
klandestine
16
0
I have attached a picture of a circuit. I am trying to find the values of I1, I2, and I3. What I have come up with so far, using Kirchhoff's Voltage and Junction Laws is:
I2=I1+I3
for the left loop:
9V - (5 ohms)I1 -4V - (10 ohms)I2 = 0
which simplifies to:
1V - (1 ohm)I1 - (2 ohms)I2 = 0
for the right loop:
14V - (10 ohms)I3 -4V - (10 ohms)I2 = 0
which simplifies to:
1V - (1 ohm)I3 - (1 ohm)I2 = 0
I am pretty certain that I have these correct, but I can't seem to solve my system of equations--whenever I try to add or subtract the equations, several terms cancel, leaving me with a current equaling zero.
I would really appreciate some help. Thank you. :!)
 

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  • #2
Answered in "introductory Physics" forum.
 

1. What are Kirchhoff's Laws?

Kirchhoff's Laws are a set of principles used to analyze electric circuits. They state that the sum of currents entering and exiting a node must be equal and the sum of voltage drops around a closed loop must be equal to the voltage supplied.

2. How do I use Kirchhoff's Laws to find current in a circuit?

To use Kirchhoff's Laws, you first need to identify all the nodes and closed loops in the circuit. Then, apply Kirchhoff's Current Law (KCL) at each node and Kirchhoff's Voltage Law (KVL) around each closed loop. Use these equations to solve for the unknown currents in the circuit.

3. Can Kirchhoff's Laws be used for any type of circuit?

Yes, Kirchhoff's Laws can be applied to any type of circuit, including series, parallel, and combination circuits. They are also applicable to circuits with multiple power sources and resistors.

4. What are some common mistakes when using Kirchhoff's Laws?

Some common mistakes when using Kirchhoff's Laws include forgetting to consider the direction of current flow and using incorrect signs for voltage drops. It is important to keep track of the direction of current and voltage in order to correctly apply the laws.

5. Are there any limitations to using Kirchhoff's Laws?

Kirchhoff's Laws are based on ideal circuit conditions and may not be accurate in real-world circuits. They also assume that all components in the circuit are linear and do not change over time. Additionally, they may become more complex and difficult to apply in circuits with multiple sources and non-linear components.

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