Question

Point charges 30 nC, - 20 nC, and 10 nC are located at (-1, 0, 2), (0, 0, 0) and (1, 5, -1) respectively. The total flux leaving a cube of side 6 m centered at the origin is

Answer 1

Points inside the cube:

 (-1, 0, 2) and (0, 0, 0).

$q_{in}=30-20=10~nC,$

$\Phi_{in}=\frac{q_{in}}{\epsilon _0}=\frac{10^{-9}}{8.85\cdot 10^{-12}}=113~Wb.$