Comment
Share
Q)

# Determine the electrostatic potential energy of a system consisting of two charges $7 \mu C$ and $–2 \mu C$ (and with no external field) placed at $(–9 cm, 0, 0)$ and $(9 cm, 0, 0)$ respectively.

$\begin{array}{1 1} -0.7\;J \\0.7\;J \\ -0.9\;J \\0.8\;J \end{array}$

$U=\large\frac{1}{4 \pi \in_0} \frac{q_1q_2}{r}$
$\quad= 9 \times 10^9 \times \large\frac{7 \times (-2) \times 10^{-12}}{0.18}$$=-0.7\;J$