(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Two charged particles are located on the x axis. The first is a charge +Q at x= -a. The second is an unknown charge located at x= +3a. The net electric field these charges produce at the origin has a magnitude of 2kQ/a^2. Explain how many values are possible for the unknown charge and find the possible values.

2. Relevant equations

3. The attempt at a solution

So what I did was that I first assumed that q is positive then if q is negative. For when I assumed it was positive, I got 2kQ/a^2= kQ/a^2 - kq/9a^2 from the formula for the electric field (I just put two equations together) and got -9Q=q. Then I tried it for when q is negative and got 9Q=k...

The problem is that the answers says that 'the field at the origin can be to the right if the unknown charge is -9Q, or the field can be to the left if the unknown charge is +27Q...'

I'm not sure if the method I used is right...because I can't seem to get +27Q...

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: The electric field

**Physics Forums | Science Articles, Homework Help, Discussion**