# Solving Resistor Circuits: Tips & Tricks

• BuBbLeS01
In summary, the conversation discusses how to calculate the current in a circuit with 2 batteries and multiple resistors. The suggested method is to replace blocks of resistors with a single equivalent resistor and to use Kirchhoff's voltage and current laws. It is also advised to label the currents in the circuit for easier calculations. The conversation ends with the mention of a specific problem involving a 12V battery, a 24 Ohm resistor, a 3V battery, and a 3 Ohm resistor, and the question of which battery to use for calculating the current.
BuBbLeS01
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## Homework Statement

I am having a hard time figuring out how to calculate the current in a circuit consisting of 2 batteries and numerous resistors. Unfortunautely the problem I am trying to do is in my book so I can't post a picture. But if someone can give me a general idea of how to approach these kinds of problems I would greatly appreaciate it!

## The Attempt at a Solution

Replace blocks of resistors in paralle with a single equivalent resistor.
Remember that voltage drops across each resistor in a circuit must add up to the battery voltage.
current through all resistors in series must bee the same.

have you learned kirchhoffs laws before? learning your concepts right before your exam is not good.

It's kind of difficult to help you if you haven't posted a specific problem. But you only need to use Kirchoff's voltage law and Kirchoff's current law here. Remember that the potential difference across a resistor is simply V = IR. Start by labeling currents in the circuit as I1, I2, I3 etc.

Well, that's all I can say without any more input from you.

EDIT: To mgb_phys advice I would add that you should always replace resistors in series with equivalent resistors. Kinda obvious I know.

This is a little off-track but it seems like you're panicking over something which you probably know how to do outside of exams. Have a look through your tutorials to refresh your memory.

Last edited:
I redrew the picture with 2 batteries 1 on each side and 2 resistors 1 on top and 1 bottom. Now that I calculated the current through the top resistor how do I work backwards to calculate the current through the each individual resistors that make up that equivalent resistor? Does that make sense?

I ended up with having a 12 V bat on the left side of the circuit then a 24 Ohm Resistor on the top, a 3 V bat on the right and a 3 Ohm Resistor on the bottom. Also how do I know which bat to use to calculate the current?

## 1. What are resistors and why are they important in circuits?

Resistors are electronic components that resist the flow of electric current. They are important in circuits because they help control the amount of current flowing through the circuit, ensuring that the components receive the right amount of electricity to function properly.

## 2. What is the difference between series and parallel circuits?

In a series circuit, the components are connected in a single loop where the current flows through each component in a specific order. In a parallel circuit, the components are connected in multiple branches and the current is divided among them. Series circuits have a single path for current to flow through, whereas parallel circuits have multiple paths.

## 3. How do I calculate the total resistance in a series or parallel circuit?

In a series circuit, the total resistance is simply the sum of all the individual resistances. In a parallel circuit, the total resistance is calculated using the formula 1/Rt = 1/R1 + 1/R2 + 1/R3 + ..., where Rt is the total resistance and R1, R2, R3, etc. are the individual resistances.

## 4. How do I use Ohm's law to solve resistor circuits?

Ohm's law states that the voltage (V) across a resistor is equal to the current (I) multiplied by the resistance (R), or V = IR. This can be used to calculate any of the three variables if the other two are known. It is a useful tool in solving resistor circuits.

## 5. Are there any tips or tricks for simplifying resistor circuits?

Yes, there are a few common tips and tricks for simplifying resistor circuits. These include using Ohm's law to calculate unknown values, combining resistors in series or parallel to reduce the total resistance, and using Kirchhoff's laws to analyze complex circuits. Additionally, using a circuit simulator or drawing a circuit diagram can also help in visualizing and understanding the circuit.

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