Question

The inward and outward electric flux from a closed surface are respectively $8\times {10}^3$ and $4\times {10}^3$ units. Then the net charge inside the closed surface is

• A. $-4\times {10}^{3}coulomb$
• B. $4\times {10}^{3}coulomb$
• C. $\frac{-4\times {10}^3}{{\epsilon }_0}coulomb$
• D. $4\times {10}^3{\epsilon }_{0}coulomb$

Answer 1

The correct option is D

$4\times {10}^3{\epsilon }_{0}coulomb$

$\frac{q_{enc}}{{ϵ}_0}={\varphi }_{net}$

$\Rightarrow q_{enc}={\varphi }_{net}\times {ϵ}_0$

Here, Net flux through the surface, ${\varphi }_{net}$ = $8\times {10}^3-4\times {10}^3$

= $4\times {10}^3$

Hence, we can calculate the enclosed charge by placing it in the above formula.