Q. The flux entering and leaving a closed surface are $5 \times 10^{5\ }$and $4 \times 10^{5\ }$MKS units respectively, then the charge inside the surface will be
A) $- 8.86 \times 10^{- 7}$C
B) $8.85 \times 10^{- 7}$C
C) $8.85 \times 10^{7}$C
D) $6.85 \times 10^{- 7}$C
Explanation
(a) Net flux leaving the surface
$\phi = 4 \times 10^{5} - 5 \times 10^{5} = - 10^{5}\ $MKS units
$\therefore\ \ $charges must be negative
$q = \phi\varepsilon_{0} = - 10^{5} \times 8.86 \times 10^{- 12}$
$= - 8.86 \times 10^{- 7\ }C$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.