# Open-circuit Req Circuit

#### Jermgilbert

Sep 10, 2020
4
I need assistance with this problem. I cannot seem to figure it out.

#### Attachments

• 20200909_223913.jpg
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#### Jermgilbert

Sep 10, 2020
4
I have tried to put it into LTspice, but cannot get it to run. I have tried grounding the open circuit ends, but that doesn't seem to work.

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,769
I have tried grounding the open circuit ends, but that doesn't seem to work.
You need one single ground only. Using multiple grounds will short circuit these parts of the circuit. Show us your LTSPICE diagram or upload the .asc file for inspection.

Provided you get the simulation up and running: how will you determine the equivalent resistance from the simulation?

#### Jermgilbert

Sep 10, 2020
4
Could I add a resistor at the end of the wires and find the total resistance that way?

#### Attachments

• Lab 1 Req.asc
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#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,769
No.
What is the usual way to determine the resistance of a component? Hint: what is the equation for R = ??? in terms of voltage and current?

#### Jermgilbert

Sep 10, 2020
4
Oh, alright I could insert a voltage source.

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,769
Good. Where? And what's next?

#### Ratch

Mar 10, 2013
1,099
I need assistance with this problem. I cannot seem to figure it out.

Ridiculously simple. Redraw the circuit.

Then use any generic equation solver or pencil and paper to solve the loop equations with a 1 volt source.

1 volt gives 1/25 amp so the resistance is 25 ohms.

Ratch

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