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Calculation of effective resistance [closed]

1 vote

Six resistors are arranged along the edges of a pyramid as shown below. The values of the resistances are shown in the figure.  

How can I find the effective resistance between A and B?

closed with the note: No Effort.
asked Nov 1, 2016 in Physics Problems by Swapnil Das (170 points)
reshown Nov 2, 2016 by xxxx
You could try applying Kirchhoff's Rules.
Alternatively, redraw the diagram in 2D as a triangle (ABC) with central point (D), with resistors connecting each pair of points. The resistors around the central point D form a Y or 'star' shape. This can be turned into an equivalent 'delta' $\Delta$ shape using the $Y-\Delta$ or 'star-delta' transform (look  it up). This leaves you with inner and outer triangles, each side being parallel resistors, which is easily reduced further and solved.
This question looks to me as a objective type question which is to be solved within 3-4 minutes.so star delta transform but would be too lengthy  and time consuming.instead this question can be solved by using symmetry .points D and C are equipotential points so we can removed the branch CD which then becomes simple series and parallel combination of resistances.
@sammygerbil would you consider removing the closed status.I think this is a good question.Thanks.
Sorry, I don't have moderator status so I cannot reopen questions. I do not think the Moderator (Einstein) will reopen unless Swapnil Das shows some effort.

Yes I think you are correct : nodes C and D are symmetrical wrt AB, so the link CD carries no current and can be removed.