00:02
Okay, so this one says that you have a charge at the corner of a cube.
00:11
And the first question asks how much flux is going through the surfaces that are touching this corner.
00:21
So that's going to be like this left surface, this bottom surface, and then the front, we'll say.
00:29
So i'm going to redraw it.
00:32
I think how understandable this video will be will be depend on a lot of my art skills.
00:40
So i hope they're good.
00:44
So along each of these surfaces, the electric field vectors are going to be parallel.
00:55
Oh, my god.
00:58
They're going to be parallel to each of the surfaces, right? so the left cube, i'll just redraw it.
01:04
It's going to look like that.
01:06
The bottom cube, excuse me, the bottom face is like that.
01:11
And then the front one is like that.
01:15
And so that means the electric fields dot product with the area vectors.
01:20
So the vectors that are perpendicular to each of these, that's always zero.
01:26
So the answer for a then is zero.
01:29
And i'm just going to triple check that i read it right.
01:32
Yeah, through each cube forming that corner.
01:37
So now the goal is to get, what about these other ones? so like right top and then back.
01:47
Oh, okay.
01:50
So that's not going to be zero, right? because the fields do kind of pierce these surfaces.
01:56
There's a non -zero dot product between the electric field vectors.
02:01
So these and then these area.
02:03
Vectors that just for clarity i will draw in green.
02:07
So these vectors that are perpendicular to each of these surfaces, so it's not zero.
02:13
And then you would hope like, oh, i hope it don't have to do this integral of like, you know, e .da, the electric field depends on where you are on the surface...