If the electric flux entering and leaving an enclosed surface respectively is `phi_1` and `phi_2`, the electric charge inside the surface will be

Options

A. `(phi_3- phi_1)/( epsi_n)`
B. `(phi_2 + phi_1)/( epsi_n)`
C. `( phi_1 - phi_3) epsi_n`
D. `epsi_n(phi_2 - phi_1)`

Answer

D

Explanation

Any closed surface is eual to the net charge inside the surface divided by `epsilon_(0))`
Let `q_(1)` be the charge , due to which flux `phi` is entering the surface (this charges will be -ve)
`q_(1)=-phi_(1)epsilon_(0)`
Let `+q_(2)` be the charge due to which flux `phi_(2)` is leaving the surface
`phi_(2)=(q_(2))/(epsilon_(0))`
`q_(2)=phi_(2)epsilon_(0)`
So , electric charge inside the surface
`=q_(2)+q_(1)=epsilon_(0)phi_(2)-epsilon_(0)phi_(1)`
`=epsilon_(0)(phi_(2)-phi_(1))`