Calculating Current in a Mixed Series and Parallel Circuit

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    Law Ohm's law
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Discussion Overview

The discussion revolves around calculating current in a circuit that contains both series and parallel components, specifically using Ohm's Law (V=IR) and effective resistance. Participants explore how to approach problems involving mixed circuit configurations, focusing on the relationships between voltage, current, and resistance.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant expresses confusion about how to apply Ohm's Law in circuits that have both series and parallel elements, noting difficulty in using effective resistance (Rt) in such cases.
  • Another participant questions the terminology used regarding calculating current and voltage, emphasizing the distinction between current through a resistor and voltage across it.
  • A later reply suggests that after finding the total effective resistance, one could calculate the total current and then use proportions to determine current through individual resistors in series and parallel.
  • One participant agrees with the approach of finding total current but notes that it is necessary to determine the individual currents (I1 and I2) for the parallel resistors.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method to calculate current in mixed circuits, with multiple approaches being discussed and some confusion remaining about the application of effective resistance.

Contextual Notes

There are unresolved assumptions regarding the specific circuit configuration and the values of resistances involved, which may affect the calculations discussed.

doublea500
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just a quick question about ohms law (v=ir) concerning when there is a parallel and a series in the same circuit. i know the rules like in a parallel, v total is v1+v2... and in a series it is 1/v+1/v2=1/vt. and that's the opposite for Current. but what do i do when there is a series and a parallel in the same question.

heres a basic question i just made. sorry its a bit dirty.

i just changed the question to help understand the concept better

The problem i have is that i can find Rt but i have no idea what to do with it because... there are 2 different things
 

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Looks like homework to me.

Looking at the questions

What do you mean calculate current from R1 etc and voltage from R1 etc?

You calculate current through a resistor and the voltage across a resistor.

If you have to calculate these for each resistor the effective resistance Rt will not help you.
 
Studiot said:
Looks like homework to me.

Looking at the questions

What do you mean calculate current from R1 etc and voltage from R1 etc?

You calculate current through a resistor and the voltage across a resistor.

If you have to calculate these for each resistor the effective resistance Rt will not help you.

so just replace from with through then :D. and how do i find the voltage and current Through these resistors without effective resistance?
 
actually, could i just find the Rt then find the Current in total. and then like separate it using proportions? like say the Rtparallel was 2 and the Rtseries was 2. and Rt in all was 4. Let's say V=8. I am just making this up now, so you don't get confused with the pic on top. so i could do V=IR->8=I*4. Itotal=2. i is the same in a series so each resistor in the series is I=2A and for the Parallel i can do the It=I1+I2... i think i got it.
 
Last edited:
That's pretty much right. You would still have to figure out what I1 and I2 are.
 

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