Three charges are placed along a line as shown.
The charges are $q_1 = 100 nC$, $q_2 = +20 nC$ and $q_3 = -75 nC$. The total distance between $q_1$ and $q_2$ is $d = 0.5 m$.
What is the distance $x$ at which the electric potential due to $q_1$ is equal to the electric potential due to $q_2$? If the electric potential is taken to be zero at infinity, how much work is required to bring $q_3$ from infinity to that position?
$x = 0.2 m, W = 0 J$
$x = 27 cm, W = -3.2 \times 10^{-5} J$
$x = 0.6 m, W = -2.3 \times 10^{-5} J$
$x = 0.3 m, W = -6.3 \times 10^{-5} J$
$x = 0.3 m, W = -1.3 \times 10^{-5} J$