2) (12 points) Consider the configuration shown below. There is a negative charge $Q_0$ at
position $x_0 = 0$ and a positive charge $Q_1$ at a position $x_1 > 0$ along the x-axis.
$Q_0$
$x_0 = 0$
$Q_1$
$x_1$
x
a) (5 points) At what position(s) $x_2 < 0$ could another positive charge $Q_2$ be added
so that the total force on $Q_0$ is 0, $F_{net} = 0$? Give your answer in terms of $x_1$, $Q_0$
and/or $Q_1$.
b) (5 points) Consider the special case where $Q_2 = Q_1$. Suppose
free to move along the x-direction, while $Q_1$ and $Q_2$ are fixed in place at $x_1$ and
$x_2$, respectively.
Draw a sketch on the graph below showing the electric potential due to $Q_1$ and
$Q_2$ $V(x)$, where $V(?) = 0$, as a function of the position x along the x-axis.
y
Identify $x_2 = -x_1$, $-1$
No superposition, $-1$
Wrong shape, $-2$
c) (2 points) Qualitatively, describe what would happen if $Q_0$ was displaced by a
small distance $?x$ to the right from $x_0 = 0$ to $x = +?x$ and then released from
this point?
