Question

How do I find the total resistance of this network? Somehow I can not figure this simple network out.

Answer 1

I know how to deal with resistors that a parallel or in a row but this configuration somehow confuses me.

Answer 2

Hmmmm I ended up with 50/3 Ohms for the total resistance.

Answer 3

Given that R3=R4, I think no electrons will flow down resistor 5.

Answer 4

But R5 is not as big as R3 so woudn´t some electrons prefer R5 over R3?

Answer 5

But they 'know' (because of repulsion of electrons in front of them, possibly) that R4 exists.

Answer 6

To find the equivalent resistance for this circuit you need to do a delta|wye conversion and then do your calculations.

Answer 7

I have never heard of a delta wye conversion.

Answer 8

tommy.. this network indeed is very complicated and you need to do a delta conversion .. however

if R1/R3= R2/R4 then the its called a balanced circuit.. and it can be proved that.. no current flows through R5 and you can chuck it!

Answer 9

Ok, but this network ist not a balaced circuit because that resistor-ratio does not fit this network.

Answer 10

Use Δ→Y transform (fast), or use 2 loops and write down all Kirchhoff's circuit laws that apply (slow).

http://en.wikipedia.org/wiki/Delta_Y

Answer 11

You can also remove R5 and use Thevenin's equivalent to find the fictitious generator between those terminals, then put R5 back in again. But this is longer.

Answer 12

using thevnin will give the load voltage and i don't think we can apply thevnin here, if you remove R5 then yes we can think of it

Answer 13

Okay, I used Kirchhoff and got now this:

Answer 14

ok this is out of my league now :D

Answer 15

i guess its 300/11 ohm =27.27 ohm

Answer 16

Are my equations alright?

Answer 17

Answer is 685/24 = 28.54 Ω.

Answer 18

There is a mistake : J5 cannot have a minus sign in eq.1 and eq.2

Answer 19

Besides, I do not understand what UR means. Are you multiplying resistance with voltage? This will not lead you anywhere.

Answer 20

-.- of course. My mistake, the Us have to be Is.
For the Equations one and two I was looking at the nodes in the middle.