Choose the incorrect statement :

$(a)$ The electric lines of force entering into a Gaussian surface provide negative flux.

$(b)$ A charge ' $q$ ' is placed at the centre of a cube. The flux through all the faces will be the same.

$(c)$ In a uniform electric field net flux through a closed Gaussian surface containing no net charge, is zero.

$(d)$ When electric field is parallel to a Gaussian surface, it provides a finite non-zero flux.

Choose the most appropriate answer from the options given below

A circular disc of radius $R$ carries surface charge density $\sigma(r)=\sigma_0\left(1-\frac{r}{R}\right)$, where $\sigma_0$ is a constant and $r$ is the distance from the center of the disc. Electric flux through a large spherical surface that encloses the charged disc completely is $\phi_0$. Electric flux through another spherical surface of radius $\frac{R}{4}$ and concentric with the disc is $\phi$. Then the ratio $\frac{\phi_0}{\phi}$ is. . . . . .

Give definition of electric flux.

A uniformly charged conducting sphere of $2.4\; m$ diameter has a surface charge density of $80.0\; \mu \,C/m^2$.

$(a)$ Find the charge on the sphere.

$(b)$ What is the total electric flux leaving the surface of the sphere?

Figure shows the electric field lines around three point charges $A, \,B$ and $C$.

$(a)$ Which charges are positive ?

$(b)$ Which charge has the largest magnitude ? Why ?

$(c)$ In which region or regions of the picture could the electric field be zero ? Justify your answer.

$(i)$ Near $A$          $(ii)$ Near $B$          $(iii)$ Near $C$    $(iv)$ Nowhere