00:05
Okay, hopefully, this is a recording.
00:11
So to approach this problem s o let me just read it again at room temperature.
00:21
What is the strength of the electric field and a twelve gauge copper riot wire with a given diameter that is needed to cause a particular current to flow.
00:29
So we want to look through the formula that release these quantities.
00:35
And that formula is given by me.
00:41
Equals the reason stimpy of the material, which is thiss given red symbol rose so well, fine.
00:48
Look up the road for copper time's a current density, and that current density is thie current per unit area flowing through the wire.
00:59
So, like, this is the wire.
01:05
Um, will has some area a it's the current for unit cross sectional area.
01:16
Um, so you can look out of the book that the resistive iti what city was a copper? um, yeah, copper.
01:27
You can look up that the resistive ity of proper is oh, let's see, point me use double check this.
01:45
Um, so i'm just gonna look at the example that they do in the book.
01:49
It's really similar.
01:50
And that's example.
01:51
Twenty five point to, um and for copper.
01:57
And that example in one point seven two times ten to the minus a o meter.
02:04
And so let me see where they get five to be.
02:07
Table twenty five one one.
02:08
Okay, there it is.
02:10
So yeah.
02:12
So then we know that row is one point seven two times ten to the minus e.
02:28
And then the current density is going to be given by the client that we want.
02:34
So that's four and a half.
02:40
And then the cross sectional area is just going to be so the formula for class sectional area is going to be pi times the radius of this process.
02:50
Small area so far.
02:55
See? okay, i'll actually let me just computed on the side, so it's going to be a pi times d over to swearing.
03:09
Uh, i'll, uh make sure to convert that sa units put money before these little units on my row while i see that.
03:17
Okay, back to the area.
03:19
So the diameters two point five millimeters.
03:22
So then the radios is half of that, which is one point o two five millimeters.
03:33
So one point oh, two, five.
03:39
It was time to minus, i swear, and yeah, so i'm just gonna leave it like that and then fried it over here.
03:55
So that's high times one point oh, two five.
04:01
And i thought if i said that, but you need to convert it to meters to keep all these and s i s units.
04:06
So your electric field, it's because the s i unit of who loans on then you kind of just take this.
04:16
Okay, so now we have the full expression for you after killed your community.
04:24
And if you plug that into repopulate, er, um, go ahead and do that...