Okay, now, there's another little part V2 and that's right here.
Notice that I forgot to do V2 and so we go 6 minus 4 across there,
and so we can see at that voltage V2 is equal to 2 volts.
So let's just write that one down also.
So V2 = 6- 4 volts, okay great,
so that's 2 volts.
Now, we need to use that down in the next one right here.
So I've already written V2 as 2 volts.
So I've written the voltage differences across here, and
what we want to find are Va, Vb, and Vc with this being our ground location.
Okay, so how do we do that?
Let's just go from maybe we can even just do the same tracks that we did before.
But let's just go from Va down to ground like this and let's just calculate it.
So we would say Va and that would be minus grounds.
So Va- 0 =, okay plus V2 which
is 2 volts plus V3 which is- 8 volts,
so now Va = 6 volts, okay?
Now, let's see what Vb is, let's go from Vb down to ground,
well Vb- 0 = plus V3 which is- 8 volts.
Now, let's get Vc.
Okay, to get Vc, let's go, here's an easy way.
We can go Va to Vc cuz we know what Va is now.
But I'm just gonna go Vc down to ground, this route right here.
So Vc minus ground 0 is equal
to plus 20 volts plus a -32 volts,
so that's = -12 volts.
Okay, now what we can observe about this circuit is,
if we move the ground around, the node voltages will in fact change.
However, the voltage differences between any two parts of the circuit
are going to stay exactly the same even as we move the ground around.
Okay, now problem 126 has you re-do this problem with the ground right here.
So why don't you stop the video, see if what you could do with a ground right
there, and check it against the solution for problem 20