00:02
Okay, in this problem, we have four little charges, q1, q2, q3, and q4, and the distances to them are labeled.
00:10
I'm going to move this so you can see.
00:14
And then we're given some magnitudes, and we are supposed to find the electric field at point p.
00:21
So i'm going to use a formula where electric field is kq over r squared.
00:29
I don't know why i put a d there.
00:30
Typically we put an r oh i do know why i put a d because it says d in the problem okay so let's look at charge one it has three e so i said k three e over d we're told is five micrometers micros 10 to the negative six so for k in your calculator you do nine times 10 to the ninth multiply by three e is the elementary charge the charge on a single electron or proton and then you have to be sure to square this denominator.
01:03
So i got one point, i got 145 newtons per coulum.
01:06
Please check my work and check my numbers.
01:10
So for the next one, i did about the same thing here.
01:15
My little fraction line went crazy, sorry.
01:18
But it's still 3e, same distance.
01:20
So i also get 145 newtons per coulum.
01:23
Again, it doesn't hurt to check that work...