Does anyone know anything about Electic charges/Electric Fields?

Question

I need major help, I don't know anythig about this!! Please help me, I am completely lost.. I'll be on IM:
Q1 = 15e-6C q = 20e-6C Q2=-10e-6C
Determine the magnitude and direction of the net electric field at the location of the charge q. The charge Q1 is 12 cm from q; the charge Q2 is 5 cm from q.

Answer 1

There's this equation called Coulomb's Law that relates charge and force: F=k*Q*Q/(r^2), where k is Coulomb's constant (8.988e9) and r is the distance between the two charges. That doesn't give us the units for an electric field, which is a force per charge. But we can divide both sides of Coulomb's Law by a Q, giving us F/q=k*Q/(r^2).



To find the magnitude and direction of the net electric field, you need to add together the electric field vectors created by each of the two charges. For the first charge, the electric field is k*15e-6/(.12^2)=9.36e6 N/C. The electric field of the second charge is k*10e-6/(.05^2)=3.60e7 N/C. Make sure to change cm to meters, and note that the charge q at which you are finding the electric field does not factor into our equation. Hopefully the problem describes in more detail the location of the two charges so you can determine the appropriate vector sum's magnitude and direction.