Skip to main content
Post Reopened by user10851, Waffle's Crazy Peanut, Alfred Centauri, Dan, Dilaton

Given 6 points that are connected with each other with a resistor of resistance $R$, find the resistance between any two points. (Answer: $R/3$)

Illustration of the problem

(allAll the conducting wires have the same resistance $R$.)

So I know that such a wording immediately implies that these 6 points are absolutely identical, which makes it possible to apply symmetry arguments that will help in reducing the network to a more simplesimpler one. 

That is, after choosing any two points in the network, we can remove the resistors which are connected between the otherremaining four points, as they remained will still be identical, and they keep the symmetry, thusso we can change betweenswap any of them and the network will remain the same. Thus, we can remove the resistors which are connected between these other four points, since the points are identical.

However, we can alsoalso swap the two chosen points, and the system will still remain the same. So why can't we also remove the resistor between the two chosen points?

I'm told of the following analogy: theThe system of these 6 points is like a system of 6 absolutely similar balls painted, say, in white. By choosing two points, we paint them in black, thus the system loosesloses some symmetry level, but its certain elements are still symmetrical under certain dispositionsrearrangements. But

Specifically, any two of the white balls can be swapped without changing the system in any way, so all the white balls are identical and we can ignore any resistors between them. But swapping the two blackblack balls still won't change the system, so why can't we follow the same logic and removeignore the resistor between the two chosen pointsthem as well?

I'll generalize the question a little bit: - why we don't care of other symmetries in the system?why don't we care about other symmetries in the system?

(I'm looking forward a simple explanation, without involving advanced math, as I'm just a self-taught beginner and meanwhile II'm only familiar with calculus. So I try to avoid matrices and anything advanced which students learn in advanced courses of electronics. I just want to get the idea and the concept itself).)

Given 6 points that are connected with each other with a resistor of resistance $R$, find the resistance between any two points. (Answer: $R/3$)

Illustration of the problem

(all the conducting wires have the same resistance $R$)

So I know that such a wording immediately implies that these 6 points are absolutely identical, which makes it possible to apply symmetry arguments that will help reducing the network to a more simple one. That is, after choosing any two points in the network, we can remove the resistors which are connected between the other four points, as they remained identical, and they keep the symmetry, thus we can change between them and the network will remain the same. However, we can also swap the two chosen points, and the system will still remain the same. I'm told of the following analogy: the system of these 6 points is like a system of 6 absolutely similar balls painted, say, in white. By choosing two points, we paint them in black, thus the system looses some symmetry level, but its certain elements are still symmetrical under certain dispositions. But swapping the two black balls still won't change the system, so why can't we follow the same logic and remove the resistor between the two chosen points?

I'll generalize the question a little bit - why we don't care of other symmetries in the system?

(I'm looking forward a simple explanation, without involving advanced math, as I'm just a self-taught beginner and meanwhile I only familiar with calculus. So I try to avoid matrices and anything advanced which students learn in advanced courses of electronics. I just want to get the idea and the concept itself).

Given 6 points that are connected with each other with a resistor of resistance $R$, find the resistance between any two points. (Answer: $R/3$)

Illustration of the problem

(All the conducting wires have the same resistance $R$.)

I know that such a wording immediately implies that these 6 points are absolutely identical, which makes it possible to apply symmetry arguments that will help in reducing the network to a simpler one. 

That is, after choosing any two points in the network, the remaining four points will still be identical, so we can swap any of them and the network will remain the same. Thus, we can remove the resistors which are connected between these other four points, since the points are identical.

However, we can also swap the two chosen points, and the system will still remain the same. So why can't we also remove the resistor between the two chosen points?

I'm told of the following analogy: The system of these 6 points is like a system of 6 absolutely similar balls painted, say, in white. By choosing two points, we paint them in black, thus the system loses some symmetry level, but its certain elements are still symmetrical under certain rearrangements.

Specifically, any two of the white balls can be swapped without changing the system in any way, so all the white balls are identical and we can ignore any resistors between them. But swapping the two black balls still won't change the system, so why can't we follow the same logic and ignore the resistor between them as well?

I'll generalize the question a little bit: why don't we care about other symmetries in the system?

(I'm looking forward a simple explanation, without involving advanced math, as I'm just a self-taught beginner and I'm only familiar with calculus. So I try to avoid matrices and anything advanced which students learn in advanced courses of electronics. I just want to get the idea and the concept itself.)

Post Closed as "Not suitable for this site" by Alfred Centauri, Qmechanic
It seems the homework tag applies even if it is not actual homework
Link
Qmechanic
  • 213.1k
  • 48
  • 590
  • 2.3k
deleted 37 characters in body
Source Link
www
  • 295
  • 1
  • 4
  • 17

Given 6 points that are connected with each other with a resistor of resistance $R$, find the resistance between any two points. (Answer: $R/3$)

Illustration of the problem

(all the conducting wires have the same resistance $R$)

So I know that such a wording immediately implies that these 6 points are absolutely identical, which makes it possible to apply symmetry arguments that will help reducing the network to a more simple one. That is, after choosing any two points in the network, we can remove the resistors which are connected between the other four points, as they remained identical, and they keep the symmetry, thus we can change between them and the network will remain the same. However, we can also swap the two chosen points, and the system will still remain the same. I'm told of the following analogy: the system of these 6 points is like a system of 6 absolutely similar balls painted, say, in white. By choosing two points, we paint them in black, thus the system looses some symmetry level, but its certain elements are still symmetrical under certain dispositions. But swapping the two black balls still won't change the system, so why can't we follow the same logic and remove the resistor between the two chosen points?

I'll generalize the question a little bit - why we don't care of other symmetries in the system?

P.S. - the answer to the original problem is $R/3$.

(I'm looking forward a simple explanation, without involving advanced math, as I'm just a self-taught beginner and meanwhile I only familiar with calculus. So I try to avoid matrices and anything advanced which students learn in advanced courses of electronics. I just want to get the idea and the concept itself).

Given 6 points that are connected with each other with a resistor of resistance $R$, find the resistance between any two points.

Illustration of the problem

(all the conducting wires have the same resistance $R$)

So I know that such a wording immediately implies that these 6 points are absolutely identical, which makes it possible to apply symmetry arguments that will help reducing the network to a more simple one. That is, after choosing any two points in the network, we can remove the resistors which are connected between the other four points, as they remained identical, and they keep the symmetry, thus we can change between them and the network will remain the same. However, we can also swap the two chosen points, and the system will still remain the same. I'm told of the following analogy: the system of these 6 points is like a system of 6 absolutely similar balls painted, say, in white. By choosing two points, we paint them in black, thus the system looses some symmetry level, but its certain elements are still symmetrical under certain dispositions. But swapping the two black balls still won't change the system, so why can't we follow the same logic and remove the resistor between the two chosen points?

I'll generalize the question a little bit - why we don't care of other symmetries in the system?

P.S. - the answer to the original problem is $R/3$.

(I'm looking forward a simple explanation, without involving advanced math, as I'm just a self-taught beginner and meanwhile I only familiar with calculus. So I try to avoid matrices and anything advanced which students learn in advanced courses of electronics. I just want to get the idea and the concept itself).

Given 6 points that are connected with each other with a resistor of resistance $R$, find the resistance between any two points. (Answer: $R/3$)

Illustration of the problem

(all the conducting wires have the same resistance $R$)

So I know that such a wording immediately implies that these 6 points are absolutely identical, which makes it possible to apply symmetry arguments that will help reducing the network to a more simple one. That is, after choosing any two points in the network, we can remove the resistors which are connected between the other four points, as they remained identical, and they keep the symmetry, thus we can change between them and the network will remain the same. However, we can also swap the two chosen points, and the system will still remain the same. I'm told of the following analogy: the system of these 6 points is like a system of 6 absolutely similar balls painted, say, in white. By choosing two points, we paint them in black, thus the system looses some symmetry level, but its certain elements are still symmetrical under certain dispositions. But swapping the two black balls still won't change the system, so why can't we follow the same logic and remove the resistor between the two chosen points?

I'll generalize the question a little bit - why we don't care of other symmetries in the system?

(I'm looking forward a simple explanation, without involving advanced math, as I'm just a self-taught beginner and meanwhile I only familiar with calculus. So I try to avoid matrices and anything advanced which students learn in advanced courses of electronics. I just want to get the idea and the concept itself).

added 144 characters in body
Source Link
www
  • 295
  • 1
  • 4
  • 17
Loading
added 266 characters in body
Source Link
www
  • 295
  • 1
  • 4
  • 17
Loading
Source Link
www
  • 295
  • 1
  • 4
  • 17
Loading