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

Two point charges q and 4q are distance L apart and free to move. A third charge is placed so that the entire three-charge system is in static equilibrium.

2. Relevant equations

[tex]\Sigma[/tex]F=0 This is the equation for static equilibrium

[tex]\vec{E}[/tex]=[tex]q/4\pi\epsilon_{0}r^2[/tex]

3. The attempt at a solution

If the three point charges are in static equilibrium, the net electric field is zero. So, [tex]\vec{E}[/tex]=0, which means that the individual electric fields of the point charges must add up to zero. Thus, the third charge must be -5q, as q + 4q = 5q.

Is any of this right?

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# Homework Help: Point charges and static equilibrium

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