# Equivalent Resistance with Wye Delta Help

Discussion in 'Homework Help' started by rodhdanan, Jun 4, 2014.

1. ### rodhdanan Thread Starter New Member

Jun 4, 2014
2
0
I have tried numerous ways to solve both these problems but i keep getting crazy numbers that in no way could be right. can somebody please tell me how to do these step by step? i know wye delta is involved but somehow im messing up the math.

Attempt at solution:
I made the 3-6-12 delta into a wye but that gave me crazy numbers that ended up being even crazier at the end.

in the second one i tried making the 2-9-20 delta into a wye and met similar problems as i did in the first one

Problems:
http://tinypic.com/r/28gv0ap/8

thank you for any help

2. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,501
512
For the second one I got 11 Ohm. Straight up parallel and series resistors, no delta-to-y transformations.

rodhdanan likes this.
3. ### rodhdanan Thread Starter New Member

Jun 4, 2014
2
0
Guess I overcomplicated the second one. I got 11 Ohms also when I tried straight parallel and series. Can't see anyway to do the same on the first one though. The cross section is tripping me up.

EDIT: Got it now. Was not taking into account the semicircle in the cross section. Can someone confirm the answer is 11.2 Ohm?

Last edited: Jun 5, 2014
4. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
The crossover is a distraction intended to test your powers of observation. A little thought should allow you to conclude the 3Ω & 6Ω are simply in parallel as are the 4Ω & 12Ω. Does that clarify anything for you?

No transformation is required.

5. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,501
512
Yep, I just saw that. I will delete my earlier post.
Edit.
Ok, I got 11.2 Ohm for the first one.