Question

The inward and outward electric flux for a closed surface in $N{m}^2/C$ are respectively $8\times {10}^3$ and $4\times {10}^3$. Then the total charge inside the surface is C.

• A. $\frac{-4\times {10}^3}{{ϵ}_0}$
• B. $-4\times {10}^3$
• C. $4\times {10}^3$
• D. $-4\times {10}^3{ϵ}_0$

Answer 1

The correct option is D $-4\times {10}^3{ϵ}_0$

According to convention, inward flux is taken negative and outward flux is positive.

Hence flux $\varphi =-8\times {10}^3+4\times {10}^3=-4\times {10}^{3}N{m}^2/C$

Now, we know that, $\varphi =\frac{q}{{ϵ}_o}$

$⟹q=\varphi {ϵ}_o$

$⟹q=-4\times {10}^3{ϵ}_o$

Answer-(D)