Electronics, a resistor Cube

  • Thread starter Dough
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  • #1
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Imagine a cube where all sides have a resistor, now remove one resistor from it and replace it with an ohmmeter, the ohmmeter reads 100ohms, calculate the resistance of each resistor. By the way each resistor is the same value.

How do you go about doign this question?
 

Answers and Replies

  • #2
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Questions like this only have one purpose: to confuse you. There is a very simple, sure-fire way of solving problems like this, and that is to re-draw the schematic in a way that makes sense. "Unwrap" the cube and draw it as a 2d schematic, and you will see that it's a trivial problem that can be solved with mesh analysis or KCL/KVL.

Edit: don't be afraid to rearrange the circuit's shape a bit, too, to make it easier to evaluate. As long as you keep the connections at the same points, the outcome will be identical.
 
  • #3
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Dough said:
Imagine a cube where all sides have a resistor, now remove one resistor from it and replace it with an ohmmeter, the ohmmeter reads 100ohms, calculate the resistance of each resistor. By the way each resistor is the same value.

How do you go about doign this question?
Can you give me an image of your cude because i nedd an illutration to answer this question
 
  • #4
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I want an image of your cube if it's possible
 
  • #5
OlderDan
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Nevek said:
I want an image of your cube if it's possible

OK here ya go. It even has the revised version for flatlanders :smile:
 

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  • #6
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There's a better way to draw a flat "resistor cube" that doesn't involve overlapping any wires.

http://img149.echo.cx/img149/5425/resistor8pc.gif

In these circuit diagram problems it always helps me to imagine the wires as these infinitely stretchy/bendable entities that just have to stay connected. Bend them around in my head a bit, then see what I can come up with.
 
  • #7
OlderDan
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dfollett76 said:
There's a better way to draw a flat "resistor cube" that doesn't involve overlapping any wires.

http://img149.echo.cx/img149/5425/resistor8pc.gif

In these circuit diagram problems it always helps me to imagine the wires as these infinitely stretchy/bendable entities that just have to stay connected. Bend them around in my head a bit, then see what I can come up with.

I think you are right. It just looks too 3D that way for my tastes :smile: , like peering into the cube through the face. I actually prefer the 3D look. The important thing is that no matter how you draw it, you have to see the six loops and deal with them.
 

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