# find equivalence resistance....

#### gaurav1292

Joined Oct 1, 2009
12

calculate d equivalent resistance b/w d terminals of d cell. d resistance of each quadrant 1.e blue one is 1 ohm and that of intersecting diameter i.e green one is 2 ohm.

i tried by distributing current in various branch but was not successful. plz tell me a way to solve this problem.

#### t_n_k

Joined Mar 6, 2009
5,448
I did it by re-drawing the circuit in a clearer format.

Then I used delta-star transformations to reduce the network to a form where simple series-parallel rules can be applied.

I calc Rtot seen by source is 2.6471 Ω

#### syed_husain

Joined Aug 24, 2009
61
hi, tnk,

i tried to solve with mesh equations. i got the same answer but the problem is it i had to solve 4 equations with 4 unknown. i tried 2 use thevemin but failed. could u pls tell me how did u do delta-Y transform?

thnx.

Last edited:

#### Tesla23

Joined May 10, 2009
374
hi, tnk,

i tried to solve with mesh equations. i got the same answer but the problem is it i had to solve 4 equations with 4 unknown. i tried 2 use thevemin but failed. could u pls tell me how did u do delta-Y transform?

thnx.
Draw a line of symmetry through it at 45° then the resistance is

2 * (0.5 + 2||(1 + 2||0.5)) = 45/17 = 2.6471

where a||b = ab/(a+b) - parallel resistors

#### t_n_k

Joined Mar 6, 2009
5,448
hi, tnk,

i tried to solve with mesh equations. i got the same answer but the problem is it i had to solve 4 equations with 4 unknown. i tried 2 use thevemin but failed. could u pls tell me how did u do delta-Y transform?

thnx.
Hi Syed,

Tesla123's method is clearly the most elegant and succinct.

If you are not sure how he did it and/or are still interested in my longer method I have included an attachment.

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#### syed_husain

Joined Aug 24, 2009
61
tesla23 and tnk, thank u very much 4 ur help. i really appreciate it.

Syed