00:01
So in this problem, powell is making a capacitor.
00:05
Oh, no, you make a capacitor.
00:07
This is a typo.
00:12
Okay, you make a capacitor by cutting a 15 centimeter diameter.
00:18
So diameter is 15 centimeters, so 0 .15 meters.
00:25
I'm just going to go ahead and find the radius, which is 0 .075 meters.
00:31
And you're going to separate them by 3 .5 millimeters.
00:39
So i'll call the separation x 3 .5 times 10 to the minus 3 meters.
00:48
And then the voltage is connected to a 6 -fold battery.
00:57
And then what's the capacitance? so a, c is equal to epsilon not a over d.
01:07
So that's epsilon not.
01:09
Since it's a circular capacitor, it's epsilon not pi r squared divided by oh, sorry, not d, but rather x.
01:17
I usually use d, but i don't want to double use it for diameter.
01:22
So i'll write that, x, x.
01:26
And then i'm going to go ahead and plug this into a calculator.
01:30
So let's see if i can remember what everything is.
01:35
8 .85 times 10 to the minus 12 times pi.
01:40
Times 0 .075 squared divided by 3 .5 times 10 to the minus 3.
01:48
So i got 4 .47 times 10 to the minus 11 ferrads.
02:02
And then for b, box this up...