Kirchoff's Rule - circuit with 3 batteries

In summary, the conversation is about a person seeking help with a problem involving finding the current through a 22 ohm resistor. They have attempted to solve the problem using Kirchoff's rules and have found the values for I1, I2, and I3. However, they are now struggling to find the voltage across points A and B. After some further attempts, they realize that their previous calculations were correct.
  • #1
brazen2
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Homework Statement


Hello everyone

I need to find the current through the 22 ohm resistor. I've tried to solve this problem for many hours now... I can't find what I'm doing wrong! Please find a rough diagram attached.


Homework Equations


Kirchoffs rules


The Attempt at a Solution


I1 + I2 = I3

top loop:

-8 -22I1+12-14I3 = 0
0.286 - 1.57I1 = I3

perimeter loop:
-8 -22I1 +12 I2 -18 =0
2.17 +1.83 I1 = I2

Inputting these numbers into the first equation:
I1+I2=I3
I1 +2.17 +1.83I1 = 0.286-1.57I1
I1 = -0.428A

I then put the I1 into the loop equations and found:
I2= 1.39 A
I3= 0.958 A

However, when I'm trying to find the voltage across the points A and B, these currents do not yield consistent voltage drops across the three portions of the circuit.

I really appreciate any help!
 

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  • #2
Sorry- i actually think this is correct. There goes a couple hours!
 
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I can see that you have correctly applied Kirchoff's rules to solve for the current through the 22 ohm resistor. However, it seems like there may be a mistake in your calculations for the voltage drops across the different portions of the circuit.

To double check your work, you can use Ohm's Law (V=IR) to calculate the voltage drops across each resistor using the currents you have found. The total voltage drop across each loop should be equal to the voltage of the battery in that loop.

If you are still having trouble, it may be helpful to redraw the circuit and label all the currents and voltage drops to make sure everything is accounted for. Sometimes a fresh perspective can help identify any mistakes.

Overall, it seems like you have a good understanding of Kirchoff's rules and how to apply them to solve circuit problems. Keep practicing and double checking your work, and you will continue to improve your skills in circuit analysis.
 

Related to Kirchoff's Rule - circuit with 3 batteries

1. What is Kirchoff's Rule?

Kirchoff's Rule, also known as Kirchoff's Voltage Law and Kirchoff's Current Law, is a set of principles that describe the behavior of electrical circuits. These rules state that the total voltage around a closed loop in a circuit must equal zero, and that the sum of currents entering and exiting a node must also equal zero.

2. How does Kirchoff's Rule apply to circuits with 3 batteries?

In circuits with 3 batteries, Kirchoff's Rule can be used to determine the voltage and current in each branch of the circuit. The total voltage around a closed loop must still equal zero, and the sum of currents at each node must still equal zero. By applying these rules, we can solve for the unknown values in the circuit.

3. Can Kirchoff's Rule be applied to circuits with more than 3 batteries?

Yes, Kirchoff's Rule can be applied to circuits with any number of batteries. The principles remain the same - the total voltage around a closed loop must equal zero and the sum of currents at each node must equal zero. However, as the number of batteries increases, the calculations become more complex.

4. What is the importance of Kirchoff's Rule in circuit analysis?

Kirchoff's Rule is essential in circuit analysis because it allows us to accurately predict the behavior and values of electrical circuits. By using these principles, we can determine the voltage and current in different branches of a circuit, and troubleshoot any issues that may arise.

5. Are there any exceptions to Kirchoff's Rule?

While Kirchoff's Rule is generally applicable to most electrical circuits, there are some exceptions. For example, in circuits with changing magnetic fields, Kirchoff's Rule may not hold true. Additionally, in circuits with non-linear components, such as diodes, Kirchoff's Rule may not apply.

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