Solve for Req with T to Delta Transform

  • Thread starter zr95
  • Start date
  • #1
25
1

Homework Statement


Find Req in the given circuit
upload_2016-9-26_13-10-23.png


Homework Equations


Series: req = r1+r2...
parallel: 1/req = 1/r1 + 1/r2 ...

The Attempt at a Solution


Without redrawing the circuit I do:
12||60 = 10
10+20 = 30
30 || 30 = 15
15+10 = 25
25||25 = 12.5
12.5+15+5 = 32.5 = Req
This is the correct answer.

upload_2016-9-26_13-10-3.png

However if I redrew the T to a delta I no longer can get the right answer.
108 || 0 = 0
(36 || 30) || (180 || 10) = 6
6||25...
and so on

Where am I going wrong in my logic? Am I not allowed to do this sort of transformation on this problem?
 

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Answers and Replies

  • #2
The Buttered Cat
Gold Member
12
6
(36 || 30) || (180 || 10) = 6
Why is the 180 in parallel with the 10?
 
  • #3
25
1
I completely looked over the 25 ohm resistor when I did that. Thanks.
 

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