Question

A charge q is placed inside a closed surface. what is the electric flux through the surface?

Answer 1

As per Gauss law  the integral of electric field vector  dot product with area vector over closed Gaussian surface = charge enclosed / epsilon

Electric flux = 
$\int \limits_{S} {\vec{E}. \vec{dS}} = \phi_E=\frac{q}{\epsilon}\\\\=\frac{q}{4 \pi \epsilon R^2}*(4 \pi R^2)=\frac{q}{\epsilon}$

Answer 2

Answer:2q/Eo

Explanation: