Find q1 such that Force on Test Charge has no X-Component

[zekester]

There are two point charges q1 located at (4,0,-3) and q2 at (2,0,1) if q2=4nC find q1 such that the force on a test charge at (5,0,6) has no x-component. I think I would know how to do this problem if I knew what a test charge was. Is it just one electron.

 

[Tide]

The point is that doesn't matter what the charge is (as long as it's not zero). If you were to place a charge $q_3$ at (5, 0, 6) what would $q_1$ have to be in order that the force acting on $q_3$ due to the electric field produced by $q_1$ and $q_2$ would give zero x component.

 

[zekester]

thanks for your help