Solving Combined circuit question

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In summary, the individual components in the circuit have been simplified and labeled for easier solving. The current through R7 must be equal to the total current, and Ohm's law can be used to determine the voltage and current for each component. By "undoing" the combinations, the values for V7 and I7 can be found.
  • #1
NeomiXD
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I've attached a conbined circuit diagram to this post. I have to solve the circuit. I know that I have to simplify the diagram into a series circuit to make it easier to solve, but I'm having trouble with a few parts in the diagram.

This is how I simplified so far:

1. I added R6 and R5 together using the series formula. I labeled it R8.

2. I added R4 and R8 together using the parallel formula. I labeled it R9.

3. I added R1, R2 and R3 together using the parallel formula. I labeled it R10.

This is where I'm having difficulty. Do I add R7 and R9 (from step 2) together using the series formula or do I leave it the way it is.
 

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  • #2
NeomiXD said:
This is where I'm having difficulty. Do I add R7 and R9 (from step 2) together using the series formula or do I leave it the way it is.

It looks as though you can add R7 + R9 + R10. They are all in series.

What you add when really depends upon what it is you're ultimately trying to solve for. If it's just the total current that the battery will be producing, then by all means reduce everything to a single resistance!
 
  • #3
I actually have to find the following:

RT = ?
IT = ?
I1 =?
I3 =?
I6 =?
I4 = ?
V2 = ?
V5 = ?
V7 = ?

I tried solving by adding R7 and R9 (from step 2) together using the series formula. I only had to find 2 more values (V7 and I7)but then I had difficulty figuring out how to find the value of V7 and I7 when only R7 was available.
 
  • #4
The current through R7 must be equal to the total current, since it is a series circuit and it is a series component of that circuit. Use Ohm's law to work out the voltage across it given the current through it.

You can always "undo" any of your combinations to get at the individual components. For example, once you solve for the total current, you know that it flows through R7, R9, and R10. Therefore you can determine the voltages across each of those resistances. Now, R10 is really three resistors in parallel. So you now have the voltage that is across each of them (parallel resistors all have the same voltage across them). So you can use Ohm's law to determine the individual currents for each of the three resistors (these currents should add up to the total current).
 
  • #5


As a scientist, it's important to approach problems systematically and with a clear understanding of the principles and formulas involved. In this case, it seems like you have made some good progress in simplifying the circuit so far. However, it's important to remember that when combining resistors in series, you add their individual resistances together, while in parallel, you use the reciprocal of their individual resistances.

In step 2, you correctly combined R4 and R8 using the parallel formula, but in step 3, you added R1, R2, and R3 using the parallel formula again. This is where the mistake lies. Since R1, R2, and R3 are already in series with each other, you should add their individual resistances together using the series formula, rather than using the parallel formula again.

Regarding R7 and R9, since they are already in series with each other, you should simply add their individual resistances together using the series formula. This will give you a simplified circuit with three resistors in series (R10, R9, and R7) that can be easily solved using the series formula.

Overall, it's important to carefully review the principles and formulas involved in solving combined circuits and make sure to apply them correctly. You may also want to double-check your calculations to ensure accuracy. Good luck with solving the circuit!
 

FAQ: Solving Combined circuit question

How do you approach solving a combined circuit question?

First, identify all the components in the circuit and their values. Then, use the laws and principles of electricity such as Ohm's law and Kirchhoff's laws to analyze the circuit. Finally, solve for the unknown values using algebraic equations.

What are the common mistakes to avoid when solving a combined circuit question?

One common mistake is forgetting to take into account the direction of current flow in the circuit. Another mistake is not properly labeling the values of components and getting them mixed up. Also, be careful to use the correct units for calculations.

How can I simplify a complex combined circuit?

To simplify a complex circuit, you can use series and parallel circuit rules to combine resistors and other components. Remember that resistors in series add up, while resistors in parallel have an equivalent resistance that is less than the individual resistances.

What is the best way to check my answer for a combined circuit question?

You can use a multimeter to measure the voltage, current, and resistance at different points in the circuit and compare them to your calculated values. Another way is to redraw the circuit and confirm that all the values and connections are correct.

Are there any shortcuts or tricks for solving combined circuit questions?

One trick is to identify any symmetrical or identical components in the circuit and use their values to simplify calculations. Another shortcut is to use Thevenin's or Norton's theorem to convert a complex circuit into a simpler equivalent circuit. Additionally, memorizing common resistor values can save time when calculating total resistance.

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