# Placing a charge

Two positive point charges are placed on the $$x$$-axis. One, of magnitude $$4Q$$, is placed at the origin. The other, of magnitude $$Q$$ is placed at $$x=3~\mbox{m}$$. Neither charge is able to move. Where on the $$x$$-axis in meters can I place a third positive point charge such that the magnitude of the net force on the third charge is zero?

Details and assumptions

• Neglect gravity.
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