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# Series Parallel Problem

#### usr13493n

Dec 28, 2018
6
How can I find the equivalent resistance?
I tried R1||R5 R24|R3+R2 and R1-5||R2-3-4

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Since we can't see your circuit we can't tell.

A simple general solution is to find a pair of resistors either in series or parallel and replace then with a single resistance of the calculated combined value. Repeat this process until there is only one resistor left.

There are circuit topologies of resistors (I think the simplest has 5 resistors) where this process can't be used to completely solve it, but as I can't see your circuit...

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,799
Since we can't see your circuit we can't tell.
Remedy: upload a circuit diagram of how your resistors are connected using the 'image' button #15 from the left in the text entry's menu bar.

#### usr13493n

Dec 28, 2018
6
Since we can't see your circuit we can't tell.

A simple general solution is to find a pair of resistors either in series or parallel and replace then with a single resistance of the calculated combined value. Repeat this process until there is only one resistor left.

There are circuit topologies of resistors (I think the simplest has 5 resistors) where this process can't be used to completely solve it, but as I can't see your circuit...

#### Attachments

• Cattura.PNG
5.9 KB · Views: 18

#### usr13493n

Dec 28, 2018
6
Remedy: upload a circuit diagram of how your resistors are connected using the 'image' button #15 from the left in the text entry's menu bar.

#### Attachments

• Cattura.PNG
5.9 KB · Views: 10

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
That circuit can't be simplified using simple formulae for resistors in series and parallel.

You need to employ another type of circuit analysis.

What other methods do you know?

#### AnalogKid

Jun 10, 2015
2,927
steve - in this forum is it ok to suggest a theorem by name without giving away the details?

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
steve - in this forum is it ok to suggest a theorem by name without giving away the details?

I guess so. I was hoping the OP would volunteer what he has been taught.

#### usr13493n

Dec 28, 2018
6
That circuit can't be simplified using simple formulae for resistors in series and parallel.

You need to employ another type of circuit analysis.

What other methods do you know?
Kirchhoff, Superposition Theorem, Series/Parallel, Current Divider, Voltage Divider and System equations

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Can you apply KVL and KCL to this circuit? Did you learn to use this to determine all voltages and currents in a circuit?

#### usr13493n

Dec 28, 2018
6
Can you apply KVL and KCL to this circuit? Did you learn to use this to determine all voltages and currents in a circuit?
I tried to use a System of equations using the Kirchhoffs Laws but nothing

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,799
I tried to use a System of equations using the Kirchhoffs Laws but nothing
Try again. That is the way to do it. Find currents and voltages in the circuit, then use the current through the voltage source to find the equivalent resistance using Ohm's law.

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
I tried to use a System of equations using the Kirchhoffs Laws but nothing

Perhaps you can post the equations you derived and we can take a look at them. You may need to post any markup you've made on the original diagram if you have added any new non-obvious variables.

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