Where can a third charge +Q be placed so that it experiences a zero force?

[shashaeee]

I'm having a hard time trying to picture the problem:

A charge of +2q is placed at the origin and a second charge of -q is placed at x= 3.0cm. Where can a third charge +Q be placed so that it experiences a zero force?

Here is how I picture the problem:

 

[berkeman]

I'm having a hard time trying to picture the problem:

A charge of +2q is placed at the origin and a second charge of -q is placed at x= 3.0cm. Where can a third charge +Q be placed so that it experiences a zero force?

Here is how I picture the problem:

View attachment 49498

The 3rd charge could end up anywhere on the line, left, right or between the first 2 charges. What is the equation for the electric field E generated by a charge at some distance...?

 

[shashaeee]

For Force its, F = KQQ/r²

The way I understand the problem is it could either be on the left or right of those two charges. Because if it was in the middle, the third charge will experience a net force directed to the right. Right?

 

[berkeman]

For Force its, F = KQQ/r²

The way I understand the problem is it could either be on the left or right of those two charges. Because if it was in the middle, the third charge will experience a net force directed to the right. Right?

Yes, that is correct. It's good that you see that.