## Homework Statement

just a questiion aren't the 1-ohm resistance(upper left) and the 3-ohm resistance in series? . The definition for resitance in series is "Two or more elements are in series if they are cascaded or connected sequentially " ,aren't they sharing the same wire? so why aren't they in series?the wire i'm talking about doesn't separate in two branches too , i'm confused
look:View attachment 54025
thanksssss

lewando
Homework Helper
Gold Member

Yes, they are in series. The 1Ω and 5Ω connected at "b" are also in series.

Yes, they are in series. The 1Ω and 5Ω connected at "b" are also in series.

Hi tahnks for your reply well i don't think they are in series because in the solution they don't use the rules of resistances in seires or parallel to solve the problem .check it out
. but i need to know why . if someone knows please explain

lewando
Homework Helper
Gold Member
Thanks for adjusting the problem statement . When you apply a voltage across a and b or a current through a and b, then there is a branch at a and at b, so they are not in series.

Thanks for adjusting the problem statement . When you apply a voltage across a and b or a current through a and b, then there is a branch at a and at b, so they are not in series.

actually the original figure doesn't show that the branch at point "a" bifurcates. it only appears in the solution , but i guess i finally get it , i think it's because black dots (nodes) mean that there is always a bifurcation . now everything makes sense , thanks !!!!!

lewando
Homework Helper
Gold Member
I read your original post literally. In my mind, a dot is a dot. To be more clear, show the attached voltage/current source. Then the branches will stand out. Glad you are clear!

I read your original post literally. In my mind, a dot is a dot. To be more clear, show the attached voltage/current source. Then the branches will stand out. Glad you are clear!

haha there is no a voltage source in this problem, the problem just say that we have to prove that equivalent resistance between "a" and "b" is 27/17 ohm.That's it.

lewando
Homework Helper
Gold Member
Well something was applied to inject a current, I, into a and outfrom b. Again, resulting in branches, therefore no series resistance.

Last edited:
SammyS
Staff Emeritus