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Okay, here's a problem that we
were working in class today, and
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I would like to just go over
this example again for you.
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We want to be able to find Vx.
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We can see we have a lot of resistors here
we can combine in series and parallel.
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Let's first color code all of our nodes.
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Here is a red node,
that's a extraordinary node.
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Here is an orange node,
that's another extraordinary node.
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Here is a blue node, also extraordinary.
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And we can see that at the bottom,
we have a black node that is also
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an extraordinary node that
includes all of these elements.
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Well let's begin by combining
our resistors in parallel.
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We can see that,
these two 16 are in parallel,
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because they are red on the top and
black on the bottom.
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When we have resistors in parallel,
we combine them in this way and
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if they happen to be
equal as the two 16 are.
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Then we end up with half
of the original resistance.
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So, when you combine these two in
parallel 16 and parallel with 16,
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it's going to give us 8.
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We can now see the 4 and
the 8 are in series,
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because they have a single
ordinary node between them.
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So, when we combine those in series
we just add them up, and the 8 and
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4 together, right here,
is going to give me a resistance of 12.
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Now, we have a 12 from yellow to black and
yellow to black,
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those two are in parallel.
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So 12 and 12 in parallel,
because of the same going to give me 6.
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Now, something cool happens here.
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I end up with a 6 on a resistance right
here, which I can bring to the other side
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of my current source and
that's because, they have the same node
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across the topic and rearrange anything
that's connected in the same nodes.
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So, my 6 is going to come over there and
then the 6 and 6 in parallel,
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is going to get me something that is 3.
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So my final circuit,
is going to look like a 10 amp current
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source in parallel with 3 ohms,
and then I have a 4 and
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let's combine these in series 8,
and I want to find this voltage.
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There's not a minus there.
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I want to find Vx.
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Now, I also can see that 8 and
4 go together in series.
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But, because I want to find Vx, I need to
leave the element that it's across and
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not combine it with other stuff or else
it will get all mixed up in my circuit.
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Now, here's the circuit that we have, and
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I'm going to show you two different
ways of being able to solve it.