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Circuits: Draw Equivalent Resistance

  • #1
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2

Homework Statement



Man, I stink at circuits. I have to simplify the 1st circuit in the image below to an equivalent resistance. I am almost there, but I am unsure of how to relate the remaining 3 resistances. In the drawing, a subscript Ri||j denotes the equivalent resistance of the two parallel resistors i and j; similarly, Ri+j is the equivalent resistance of the two series resistors i and j.

Now, I am not sure how to relate [itex]R_1,\,R_{(3||4)+5},\,R_2[/itex] and I think my confusion lies in the fact that I do not know what is going on with the current in this last circuit. Can someone help me out with that?

Screenshot2011-01-22at121832PM.png
 

Answers and Replies

  • #2
Delphi51
Homework Helper
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You have it pretty well finished! Just combine the R(3||4)+5 with the R2 in parallel. That result is in series with R1.
 
  • #3
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2
You have it pretty well finished! Just combine the R(3||4)+5 with the R2 in parallel. That result is in series with R1.
OK! Now, this is because after the current leaves R1, it splits among R2 and R(3||4)+5 so we combine them in parallel. Right?

Thanks again Delphi!
 
  • #4
gneill
Mentor
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They combine in parallel because they *are* in parallel! Look at how their leads connect.
 
  • #5
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They combine in parallel because they *are* in parallel! Look at how their leads connect.
Hi gneill! I don't understand your reply!
 
  • #6
Delphi51
Homework Helper
3,407
10
I think you are both saying the same thing! Parallel means both ends of the resistors are connected together AND that the current splits between them.
 

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