# Symmetry in circuits involving Resistors

Discussion in 'Homework Help' started by logearav, Nov 18, 2015.

1. ### logearav Thread Starter Member

Aug 19, 2011
248
0
Hello friends,
Find attached a problem involving symmetry in circuits involving resistors. Its been mentioned that by symmetry the current in part ab and ad will be equal.
The current i branches to part d, o and b at the same time. Then how could symmetry is applicable only in ad and ab not ao?

2. ### logearav Thread Starter Member

Aug 19, 2011
248
0
Also please refer the following attachment too.
Why there is symmetry as mentioned?

3. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
Are the resistors all the same value? That's critically important to know.

Assuming so, who says that it doesn't apply to ao?

4. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
Well, look at those two branches. Is there any reason for the current in one to be different than the current in the other?

5. ### logearav Thread Starter Member

Aug 19, 2011
248
0
Thanks Mr.WBahn. By symmetry does it mean that the magnitude of current is same in every branch?
Yes, the resistances are of equal value.

6. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
Symmetry does not necessarily mean that the magnitude of the current is the same in every branch, just in those to which the particular symmetry argument applies.

7. ### logearav Thread Starter Member

Aug 19, 2011
248
0
Thanks. So what exactly symmetry means with respect to current, sir?

8. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
It means that there is no reason for the current in one resistor to be different than the other. The usual test for this is that you could swap the paths and nothing would change.