Coulomb's Law (Electric Force) Video Lessons

Concept

# Problem: Three charged particles are arranged along a line as in this figure.What is the charge on particle 3?

###### FREE Expert Solution

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 q1 and q2 are charges separated by distance r.

From Coulomb's law, F12 is:

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

88% (342 ratings)
###### Problem Details

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

What is the charge on particle 3?