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2023-12-09 18:17:22 -08:00
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commit 6a5e02a8ac
27 changed files with 36 additions and 33 deletions

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@ -168,7 +168,7 @@ Using Ohm's law and Kirchoff's law, calculate the effective resistance $R_{\text
\pagebreak
We can now use effective resistance to simplify complicated circuits. Whenever we see the above constructions
(resistors in parellel or in series) in a graph, we can replace them with a single resistor of appropriate value.
(resistors in parallel or in series) in a graph, we can replace them with a single resistor of appropriate value.
\problem{}
@ -243,13 +243,13 @@ If we place $A$ and $B$ at opposing vertices, what is the effective resistance o
and $B$ at \texttt{111...1}. We can divide our cube into $n+1$ layers based on how many ones are in each
node's binary string, with the $k^\text{th}$ layer having $k$ ones. By symmetry, all the nodes in each layer
have the same voltage. This means we can think of the layers as connected in series, with the resistors
inside each layer connected in parellel.
inside each layer connected in parallel.
\vspace{2mm}
There are $\binom{n}{k}$ nodes in the $k^\text{th}$ layer. Each node in this layer has $k$ ones, so
there are $n - k$ ways to flip a zero to get to the $(k + 1)^\text{th}$ layer. In total, there are
$\binom{n}{k}(n - k)$ parellel connections from the $k^\text{th}$ layer to the $(k + 1)^\text{th}$
$\binom{n}{k}(n - k)$ parallel connections from the $k^\text{th}$ layer to the $(k + 1)^\text{th}$
layer, creating an effective resistance of
$$
\frac{1}{\binom{n}{k}(n - k)}