Equivalent resistance of tricky circuits?

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asifrulzz
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equivalent resistance of tricky circuits?

Homework Statement


what is the equivalent resistance between A and B?
Resistor network diagram in a diamond layout with corner nodes E, A, G and C and inner nodes J, D, H and B. Each edge is labelled R, with 3I currents marked at C and A.



Homework Equations


kirchoffs law for voltage and current


The Attempt at a Solution


i got the equivalent resistance between A to C as 3R/4
but i have to find the resistance between A to B but point B is in the middle of the circuit and i don't know how to approach it
i am stuck on this
please help!
 
Last edited:
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asifrulzz said:

Homework Statement


what is the equivalent resistance between A and B?https://www.physicsforums.com/attachments/43813


Homework Equations


Kirchhoff's Law for voltage and current


The Attempt at a Solution


i got the equivalent resistance between A to C as 3R/4
but i have to find the resistance between A to B but point B is in the middle of the circuit and i don't know how to approach it
i am stuck on this
please help!
Hello asifrulzz. Welcome to PF !

No attachment found !
 


i have always calculated equivalent resistance at the ends
i don't have any idea how i would reach at point B which is in the middle
 


The network of resistors is equivalent with a cube of resistors. You can use that the equivalent points are at equal potential if you connect a voltage source between points A and B, and can be connected with a wire.

ehild
 
Attachments
  • Left: a cube with vertices labelled B, J, D, E, H, A, G, C and F, with the front face shaded magenta and the top face shaded yellow. Right: a resistor network drawn as a diamond with each edge a resistor R, nodes labelled E, G, A, C, B, D and H, with current 3I entering at A and leaving at C, and yellow, magenta and grey shading on the faces.
    cubes.JPG
    17.1 KB · Views: 2,113
Last edited:
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A step ahead: The points D,E,G of the cube are equivalent and can be connected with a wire. The same holds for J, H, C.

ehild
 
Attachments
  • Left: a cube wireframe with vertices labelled A through J, some marked red or blue, with yellow and magenta faces. Right: a flattened graph of the same cube with nodes D, E, G, J, H, C, A and B, joined by lines, linked by an equals sign.
    cuberes.JPG
    11 KB · Views: 1,752