Solving Circuits with Resistors: Finding Req and Applying the VIR Chart

In summary, the conversation discusses a problem involving calculating the equivalent resistance (Req) of a circuit and using a VIR chart to solve it. The individual is having trouble with the VIR chart and is seeking confirmation of their thought process in solving the problem. They mention working backwards from Req and using the Loop Law to determine the voltage and current for different components in the circuit. However, they are unsure if their approach is correct and are seeking feedback.
  • #1
megaboy123

Homework Statement


https://s10.postimg.org/lb6n94ua1/20161007_190700.jpg

Homework Equations


V=IR

The Attempt at a Solution


So far I haven't had any problems finding the Req. However, I am having trouble with the VIR chart. Can anyone confirm whether or not I did it correctly. My thought process was that I would work backwards from the Req knowing whatever is in series will have the same current and parallels have same voltage. I tried applying the Loop Law as well knowing those 2 properties.

For example, I know that R2345 is has a certain R but also has the same current as R1. Knowing this I I found the voltage for R2345 and divided by 2 to find the voltage for R234 and R5.

You don't have to post your own solutions, although they would help me figure out what's wrong, but I just need to know if I am on the right path using the following thought process.
 

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  • #2
Hi megaboy123, Welcome to Physics Forums!

It's not clear what the problem is. Can you provide a problem statement that describes what you are given and what is to be done or calculated? Set the scene for us? For example, is the VIR chart something provided as part of the problem, or something you filled out from another step that we don't see? Remember, none of us here are in your class or have seen your labs or assignments.
 
  • #3
We seem to be missing a problem statement here. Please edit this and indicate what the problem is.
 

1. What is the purpose of finding Req in a circuit?

The equivalent resistance (Req) is the total resistance of a circuit, which is important in determining the overall current and voltage in the circuit. It allows us to simplify the circuit and make calculations easier.

2. How do you calculate Req in a circuit with resistors in series?

In a series circuit, the Req is simply the sum of all the individual resistances. So, Req = R1 + R2 + R3 + ...

3. Can you explain how to use the VIR chart to solve circuits with resistors?

The VIR chart is a tool used to organize and visualize the relationships between voltage (V), current (I), and resistance (R) in a circuit. By filling in any two values and using Ohm's Law (V = IR), we can find the missing value and use it to solve for Req.

4. How do you calculate Req in a circuit with resistors in parallel?

In a parallel circuit, the calculation for Req is more complex. It is equal to the reciprocal of the sum of the reciprocals of each individual resistance. So, 1/Req = 1/R1 + 1/R2 + 1/R3 + ...

5. Can you provide an example of solving a circuit with resistors using the VIR chart?

Sure! Let's say we have a circuit with a 10-ohm resistor and a 20-ohm resistor in series, and a voltage source of 12 volts. Using the VIR chart, we can fill in the values of V = 12 and R = 10 to solve for I. Using Ohm's Law, we get I = V/R = 12/10 = 1.2 amps. We can then use this value to find the Req by using the equation V = IR with the other resistor, so 12 = 1.2 x Req. Solving for Req, we get 10 ohms. So, in this circuit, the equivalent resistance is 10 ohms, and the current is 1.2 amps.

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