Add Resistors: Solve Circuit Value

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Homework Help Overview

The discussion revolves around a circuit problem involving the addition of resistors to find an equivalent resistance. The original poster expresses difficulty in determining how to combine the resistors correctly, specifically identifying which resistors are in series and which are in parallel.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the definitions of series and parallel resistor configurations. The original poster attempts to apply formulas for series and parallel resistances but struggles with the circuit's layout. Questions arise about the relationship between the 3 ohm resistor and the 2 ohm resistors, as well as the identification of parallel pairs.

Discussion Status

The conversation is ongoing, with participants providing clarifications on the definitions of series and parallel connections. Some guidance has been offered regarding how to approach combining the resistors, but there is no explicit consensus on the correct method to find the total resistance.

Contextual Notes

The original poster mentions a specific expected answer of 2 ohms, which may influence their reasoning. There is also a suggestion that the circuit's visual representation may be impacting the understanding of the connections.

magnifik
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Homework Statement



http://img8.imageshack.us/img8/4413/81107636.jpg

i'm a noob, and i am having trouble adding resistors. this circuit can be reduced to 1 resistor. what is its value?

Homework Equations


parallel: 1/Rtot=1/R1+1/R2+1/R3+1/R4
series: Rtot=R1+R2+R3+R4

The Attempt at a Solution


so i thought 3, 2, 2 added up in series and you just do 6/8+1/4, but this isn't right. =/ I'm having trouble discerning which resistors are parallel and which are in series. any help would be appreciated.
 
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2 resistors R1 and R2 are in series if one connector of R1 is connected to a connector of R2 and nothing else is connected to these connectors. (or if you can determine that no current can flow through such a connection)

None of the resistors here is in series with any other.
The 3 ohm resistance isn't in series with any of the 2 ohm resistances because the point between the 3 ohm resistance and any of the 2 ohm resistances is also connected to the other 2 ohm resistance

2 resistors are parallels if one connector of R1 is connected to a connector of R2 and the other connector of R1 is connected to the other connector of R2. There's only 1 pair of
resistances here that's parallel.

The direction they are drawn in doesn't matter.

Once you combined those resistances, you can look again for a pair of resistances that is in series or parallel.
 
huh? so are you saying i can disregard the 3 Ohm resistor?
i know the answer is supposed to be 2. i don't know how to get there though.
 
magnifik said:
huh? so are you saying i can disregard the 3 Ohm resistor?
i know the answer is supposed to be 2. i don't know how to get there though.

No. I said the 3 ohm resitor isn't in series with any of the 2 ohm resistances. What you have to do is find the pair of resistances that's parallel, combine those and then look for other series of parallel pairs
 
is 3 parallel with 4 and 2 is parallel with 2?
 

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