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Resistor Network

  • #1
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0

Homework Statement



Show that the equivalent resistance is Req = 1/2 [(4RtRl + Rt^2)^(.5) + Rt]
http://img74.imageshack.us/img74/5905/pingib2.png [Broken]

Homework Equations





The Attempt at a Solution



So far all I can get is Req = Rt + Rl Rt/(Rt+Rl) from the first three resistors starting from the left. I suppose I could take that and add it to the next branch Rl Rt/(Rt+Rl), but that would appear to go on to infinity as opposed to stopping at a nice number.

Does anyone have any hints on finding the eq. resistance?
 
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Answers and Replies

  • #2
Astronuc
Staff Emeritus
Science Advisor
18,704
1,717
I believe by recursion.

Everything to the right of RL is parallel with RL, and in series with RT.
 
  • #3
Since this is an infinite circuit, ignore the first rt and rl, and assume the resistance of the rest to be R. This give you:

R*rl/(R+rl) +rt=R. As the resistance of the total circuit is also R. Solve for R to get your answer.
 

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