Force on a Point Charge: Finding the Location of a Third Charge

[acherentia]

Homework Statement

2 particles of charge q and -2q are located as shown in http://s966.photobucket.com/albums/ae146/acherentia/ . A third charge Q is placed on the x-axis and it is found that the total electric force on Q is zero. In which region of the figure is Q located?

Homework Equations

Coulomb's Law

The Attempt at a Solution

F1 + F2 = 0

F1(q on Q) = ?

F2(-2q on Q) = ?

What exactly does it mean a charge of -2q? Is it the same as the charge of 2 electrons?

 

[tiny-tim]

Hi acherentia!

What exactly does it mean a charge of -2q? Is it the same as the charge of 2 electrons?

It just means that the second charge is minus twice the first charge …

it could be one proton and two electrons, or just one coulomb of positive charge and two coulombs of negative charge, or any such combination.