# Were is the electric field zero?

blackblanx

## Homework Statement

What is the net electric field intensity at the origin due to two charges Q1= 2$$\mu$$C at (x=3,y=4) and Q2 = -10$$\mu$$C at (x=6,y=-8). And where should a third charge of magnitude 5 $$\mu$$C be placed so the net electric field at the origin is zero?

## Homework Equations

E=KQ/R$$^{2}$$ $$\widehat{r}$$

## The Attempt at a Solution

I have found the first part of the question to be E= 3236$$\widehat{i}$$-10069$$\widehat{j}$$ but I am not sure how you would find out were to place the third charge. Please help

Homework Helper
Hi blackblanx! (have a mu: µ )
… And where should a third charge of magnitude 5 $$\mu$$C be placed so the net electric field at the origin is zero?

I have found the first part of the question to be E= 3236$$\widehat{i}$$-10069$$\widehat{j}$$ but I am not sure how you would find out were to place the third charge. Please help

The third charge will have to supply a field of minus E. blackblanx
Hi blackblanx! (have a mu: µ )

The third charge will have to supply a field of minus E. but what are the coordinates of where that charge should be placed?

blackblanx
oh wait never mind i think i got it know thanks it would just be the negative of the electric field vector divided by k(5$$\mu$$C)

blackblanx
Forget I realized that does not work any ideas of how to find the coordinates?

It'll be on the line in the direction of E, at the distance appropriate to the given strength. 