Assertion : Electric lines of force never cross each other.

Reason : Electric field at a point superimpose to give one resultant electric field.

In a region of space the electric field is given by $\vec E = 8\hat i + 4\hat j+ 3\hat k$. The electric flux through a surface of area $100\, units$ in the $x-y$ plane is....$units$

Find out the surface charge density at the intersection of point $x =3\, m$ plane and $x$ -axis, in the region of uniform line charge of $8\, nC / m$ lying along the $z$ -axis in free space.

How field lines depend on area or on solid angle made by area ?

If $\oint_s \vec{E} \cdot \overrightarrow{d S}=0$ over a surface, then:

Four closed surfaces and corresponding charge distributions are shown below

Let the respective electric fluxes through the surfaces be ${\phi _1},{\phi _2},{\phi _3}$ and ${\phi _4}$ . Then