Gauss's law and Coulomb's law , although expressed in different forms , are equivalent ways of describing the relation between charge and electric field in static conditions . Gauss's law is `epsilon_(0) phi = q_(encl)`,when `q(encl)` is the net charge inside an imaginary closed surface called Gaussian surface. The two equations hold only when the net charge is in vaccum or air .
A Gaussian surface encloses two of the four positively charged particles. The particles that contribute to the electric field at a point `P` on the surface are

Options

A. `q_(1)` and `q_(2)`
B. `q_(2)` and `q_(3)`
C. `q_(4)` and `q_(3)`
D. `q_(1) , q_(2) , q_(3)` and `q_(4)`

Answer

D

Explanation

Electric field is always net electric field in the formula `int E . Ds = (q)/(epsilon_(0))`
Since `q` is the charge inside the closed surface , `E_(p)` is due to `q_(1) , q_(2) , q_(3) , and q_(4)`.