00:01
So for this question, you can solve it by first setting up a diagram.
00:07
Charge a, mystery charge, and positive three microculems throughout.
00:17
So to find the mystery charge, we basically need to find the charge that would generate the force needed to counter the force of repulsion between charge a.
00:28
Turn in the right -hand corner in order for the net charge, that force, net force, to point in the vertical direction.
00:34
So to do that, we can link these all together like the right triangle.
00:41
By doing that we create an angle here that we can solve for.
00:46
We can use tangent because we have these values, d and 4d.
00:52
So tangent is opposite over adjacent, d over 4d.
00:56
Ds cancel out.
00:58
To solve for theta, you can just take the inverse tangent of 1 -4th to give you 14 degrees.
01:05
That's theta.
01:05
Now once you have that, you can basically set up a cosine of theta to find the hypotenuse.
01:17
Now the hypotenuse includes the q charge.
01:21
So once we've had that, we can isolate q set up for it...