Answer:
Step-by-step explanation:
a )
The Gaussian surface must have contained both the charges like +3 nC and - 3 nC , total charges being zero . According the Gauss's law , total electric flux over a closed surface is equal to 1 / ε₀ times the total charge contained inside the closed surface .
Since total charge inside is zero , total flux will be 1 / ε₀ x 0 = 0
b )
In this case the Gaussian surface is so small that it contains only the charge
+ 3 nC .
So electric flux over the Gaussian surface
= ( 1 / ε₀ ) x 3 x 10⁻⁹
= (1 / 8.85 x 10⁻¹² ) x 3 x 10⁻⁹
= 3 x 10³ / 8.85
= 339 weber.
=