Find Equiv. Resistance of Circuit: R1, R2, R3, R4

In summary, the problem involves finding the equivalent resistance of a circuit consisting of four resistors, with some connected in series and others in parallel. After some confusion and clarification, it is determined that the top two resistors are in parallel and the bottom two are in parallel, with the two parallel parts then being in series. The final equation for the equivalent resistance is (R1||R4)+(R2||R3).
  • #1
Atlos
11
0

Homework Statement


I'm just trying to find the equivalent resistance of this:
http://sogacity.com/images/circuit.png


Homework Equations


Resistors in series add and resistors in parallel inversely add.


The Attempt at a Solution


I'm not even sure how to approach this. I guess I can't get my head around how it is set up. R1 and R2 are in series, but being connected to R3 and R4 in multiple places is what's confusing me. If somebody could help me create an equation for the equivalent resistance of all of that I would be thankful.
 
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  • #2
Follow the path from the power source around the outside of the drawing. No resistors.
 
  • #3
Do you mean like this?

http://sogacity.com/images/circuit2.png

So would R1 and R2 be in parallel with R3 and R4? Like (R1 + R2)||(R3 + R4)?
 
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  • #4
Because there is a continuous path around the resistors, they are shorted out and have no effect. So, the resistance is zero.
 
  • #5
Ah I understand it now, not sure how I missed that. Thanks!
 
  • #6
Uggh, I knew it couldn't be that easy! I drew a wire where there shouldn't have been one. This is the real circuit:

http://sogacity.com/images/circuit3.png

Anyways, I still have no idea how to approach this problem. Would it be (R1||R4)+(R2||R3) since R1 and R2 seem to be in series and R1R4 and R2R3 look to be in parallel?
 
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  • #7
It looks like they touch at the centre point.

So, yes, the top two are in parallel and the bottom two are in parallel and then the two parallel parts are in series.

It might look more familiar like this:

[PLAIN]http://dl.dropbox.com/u/4222062/series%20parallel.PNG
 
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  • #8
Awesome, thanks a lot.
 

FAQ: Find Equiv. Resistance of Circuit: R1, R2, R3, R4

What is the purpose of finding the equivalent resistance of a circuit?

The equivalent resistance of a circuit is the total resistance that replaces all the individual resistances in a circuit. It is useful for simplifying complex circuits and calculating the total current and voltage in a circuit.

What is the formula for finding the equivalent resistance of a circuit with resistors in series?

The formula for finding the equivalent resistance of resistors in series is Req = R1 + R2 + R3 + ... + Rn, where R1, R2, R3, ... , Rn are the individual resistances in the circuit.

What is the formula for finding the equivalent resistance of a circuit with resistors in parallel?

The formula for finding the equivalent resistance of resistors in parallel is 1/Req = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn, where R1, R2, R3, ... , Rn are the individual resistances in the circuit.

How do I determine the total resistance in a circuit with both series and parallel resistors?

To determine the total resistance in a circuit with both series and parallel resistors, you can use the formula Req = Rs + Rp, where Rs is the equivalent resistance of the series resistors and Rp is the equivalent resistance of the parallel resistors.

Can I use the equivalent resistance to calculate the total current and voltage in a circuit?

Yes, you can use the equivalent resistance to calculate the total current and voltage in a circuit. The total current is equal to the voltage divided by the equivalent resistance (I = V/Req). The voltage across each individual resistor can also be calculated using Ohm's law (V = IR).

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