00:01
All right, so we have a potentialometer in series with a ordinary resistor, and these are all in series with a battery.
00:09
So let's say, we've got our battery here.
00:12
We have a ground connection between them, which we don't need to worry about at the moment.
00:18
And then, right, so there's some point b that we're going to evaluate a couple things out.
00:23
And then we have our potentiometer here.
00:28
So i believe i have everything drawn correctly.
00:30
So the voltage of this battery is 71 .5 volts.
00:34
This is a 2 .68k resistor.
00:40
And we want to know a couple of things about this.
00:44
So first off, we're told that's sort of like the resistance per millimeter of this potentiometer is 375 oms per millimeter.
00:57
So every millimeter that we turn this wiper on this thing, we get 375 additional oms of resistance and we want to know what how far must we turn this wiper so what must this distance be x so that the current flowing through point b is 10 .8 mlliams and so in regular amps this is 0 .018 amps okay so to do this we first need to find what for this given amperage what must the total resistance in the the circuit b and then we subtract out this 2 .68k from that to get what the resistance of this resistor must be the potentiometer and then from there we can figure out what the distance needs to be so the total resistance in a circuit is just going to be the voltage supplied divided by the current in the circuit so our voltage is 71 .5 volts we have 10 .8 millie amps and so this is going to give us a total resistance of about 6 .62 ,000 oms...