00:01
We'd like to find the electric field at point p.
00:03
We're given our radius.
00:06
We can resolve our electric fields along the x -axis.
00:09
E along our x -axis is e -a -p times cosine of 30 plus e -p -c times cosine of 30 degrees minus e -b -p, which i'll call this a, b, and c.
00:25
And we already have our point p.
00:28
Eap is equal to kqa over r squared.
00:32
So we plug in 9 times 10 to the 9 times our 3 times 10 to the negative 9 divided by 3 .60 times 10 to the negative 2 squared and we'll get our electric field there.
00:45
So let's plug that in.
00:46
9 times 10 to the 9 times 3 times 10 to the negative 9 divided by 3 .60 times 10 to the negative 2.
00:57
Squared, we get 20833 .3 0 .3 nons per coulum.
01:05
Similarly, ebp is equal to kqb over r squared.
01:11
So now we just change our charge.
01:15
So qb is negative 2 nanoculomes.
01:19
Our radius is going to still be the same.
01:23
So we get our charge to be negative 13888 .8 .8 .8 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .n .n .n .n .n .n .n .n .nnnnnnnnnnnnnnnnnnnnnnnnn our our per coulum.
01:34
But since it's a magnitude, let's just keep this positive.
01:37
An epc is equal to k qc divided by r squared.
01:42
Now we plug in our charge c, which is three nanoculums, and we get 2833 .3 0 .3 .0 .0...