Question

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

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

Answer 1

Answer: (B)

Flux = $\frac{q}{{\epsilon }_0}i.e.q={\epsilon }_0\times$ flux = ${\epsilon }_0$ (8 - 4) 10${}^3$ = 4 $\times 10^3{\epsilon }_0$
Net charge inside the surface = - 4 $\times 10^3{\epsilon }_0$