(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I have 2 charges:

Q1 = 300 uC located at (1, -1, -3) m

Q2 = ?? uC located at (3, -3, -2) m

Q1 feels a force from Q2 of F1=(8i - 8j + 4k) N

1. Find Q2

2. Find the expression of the E-Field at (3, -3, -2) m (at Q2)

2. Relevant equations

F=(k|Q1*Q2|) / r^2

E=(k|q|) / r^2

3. The attempt at a solution

For the first part I've used the magnitudes:

Q1 = (1, -1, -3) m = [tex]\sqrt{1^2 + -1^2 + -3^2}[/tex]

F1 = (8i - 8j + 4k = 4 N

I found the distance between Q1 and Q2 using pythagorean formula: 3 meters.

Then I solved for Q2 using Coulomb's Law:

Q2 = 13.3 uC

For the second part, I know that since they ask for the expression of the electric field at the location of Q2, Q2 will not contribute to the value. Beside that, I'm a bit lost.

Do I need to use the distance between Q1 and Q2, then solve for E=k|q| / r^2? What's |q| in this case?

Thanks!

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# Homework Help: Expression of Electric Field with known charges

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