00:01
Now let's talk about another type of circuit.
00:03
So if we had a circuit with a battery potential, let's say v of the battery is equal to 240 volts.
00:14
All right, and let's say this is a series circuit.
00:17
So all the resistors are going to be in series with each other.
00:26
And let's say we have three.
00:27
I think three may be enough.
00:31
Let's say we don't know r1.
00:33
We know r2.
00:34
Let's say r2 is equal to 16 ohms.
00:39
And r3 is equal to 12 ohms.
00:48
So if we know the current that's going through this circuit, this is i.
00:55
If we know the current, first of all, the current that's going through the circuit since it's series, it's going to be the same current going through all of these resistors.
01:02
And it's the same current that goes back into the battery and comes out the battery.
01:11
So the current will be the same.
01:12
The current, let's go ahead and say that's equal to 5 amps.
01:17
So our job is to figure out what the resistance is in the first resistor.
01:22
Okay, now the idea behind kirchhoff's loop law says that the potential, let's say at the battery, potential at the battery for a series circuit especially, should be equal to the sum of all the potential drops over the electrical devices.
01:42
So you'll have potential drop at each one of these electrical devices.
01:46
So it should be equal to v1 plus v2 plus v3.
01:51
Another way to write this is that the energy from the battery will be dissipated over all of the resistors in order to cause the circuit to move, you know, correctly.
02:10
And so i can do this one or two ways.
02:12
I think i'm going to choose the way, it doesn't really matter actually, but i'll choose the first equation.
02:19
So we know the potential at the battery.
02:21
We just need to find the potential drops at r2 and r3...