# E-feild and stuff

1. Jan 19, 2004

### keeganisafish

I really need help, and I'd greatly appreciate it.

"Two point charges of +10nC and -20nC lie on the x-axis at points x=0 and x=+10m, respectavly. Find the point where the net electric feild is zero, if such a point exists."

The teacher gave us the answer 24m, and I just can't see how!!!

You help is REALLY APPRECIATED, I have been on this one forver it seems...

I keep getting 20m?

Last edited by a moderator: Jan 19, 2004
2. Jan 19, 2004

### himanshu121

Show your solution sheet where u got 20 m

24m is correct

3. Jan 19, 2004

### keeganisafish

I did

k*10nC&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;k(-20nC)
-------&nbsp;&nbsp;&nbsp;--------
(10m)^2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(d-10m)^2

And solved for d

4. Jan 20, 2004

### himanshu121

It should be
$$\frac{k*10nC}{r^2}-\frac{k*20nC}{(10+r)^2}=0$$

coz fields adds upto zero on the position left to origin

i should say for x=-24

Last edited: Jan 20, 2004
5. Jan 21, 2004

thanks!!