In this problem, we're going to use Coulomb's law:

$\overline{){\mathbf{F}}{\mathbf{=}}\frac{\mathbf{k}{\mathbf{q}}_{\mathbf{1}}{\mathbf{q}}_{\mathbf{2}}}{{\mathbf{r}}^{\mathbf{2}}}}$, where F is the electric force, k is Coulomb constant, and q_{1} and q_{2} are charges separated by distance r.

From Coulomb's law, F_{12} is:

$\begin{array}{rcl}{\mathbf{F}}_{\mathbf{12}}& \mathbf{=}& \frac{\mathbf{k}{\mathbf{q}}_{\mathbf{1}}{\mathbf{q}}_{\mathbf{2}}}{{{\mathbf{r}}_{\mathbf{12}}}^{\mathbf{2}}}\\ & \mathbf{=}& \frac{\mathbf{(}\mathbf{9}\mathbf{\times}{\mathbf{10}}^{\mathbf{9}}\mathbf{)}\mathbf{(}\mathbf{4}\mathbf{.}\mathbf{0}\mathbf{\times}{\mathbf{10}}^{\mathbf{-}\mathbf{9}}\mathbf{)}\mathbf{(}\mathbf{2}\mathbf{.}\mathbf{0}\mathbf{\times}{\mathbf{10}}^{\mathbf{-}\mathbf{9}}\mathbf{)}}{{\mathbf{(}\mathbf{10}\mathbf{\times}{\mathbf{10}}^{\mathbf{-}\mathbf{3}}\mathbf{)}}^{\mathbf{2}}}\end{array}$

Three charged particles are arranged along a line as in this figure.

What is the charge on particle 3?

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Our tutors have indicated that to solve this problem you will need to apply the Coulomb's Law (Electric Force) concept. You can view video lessons to learn Coulomb's Law (Electric Force). Or if you need more Coulomb's Law (Electric Force) practice, you can also practice Coulomb's Law (Electric Force) practice problems.