A charge $q$ is placed at the center of one of the surface of a cube. The flux linked with the cube is :-

An electrostatic field line leaves at an angle $\alpha$ from point charge $q_{1}$ and connects with point charge $-q_{2}$ at an angle $\beta\left(q_{1}\right.$ and $q_{2}$ are positive) see figure below. If $q_{2}=\frac{3}{2} q_{1}$ and $\alpha=30^{\circ}$, then

A point charge $q$ is placed on the centre of a hemispherical surface as shown in figure.The net flux of electric fietd tnroug the hemi-spherical surface is closest to

$(a)$ An electrostatic field line is a continuous curve. That is, a field line cannot have sudden breaks. Why not?

$(b)$ Explain why two field lines never cross each other at any point?

A square surface of side $L$ metres is in the plane of the paper. A uniform electric field $\vec E(V/m) $, also in the plane of the paper, is limited only to the lower half of the square surface, (see figure). The electric flux in SI units associated with the surface is

A cone of base radius $R$ and height $h$ is located in a uniform electric field $\vec E$ parallel to its base. The electric flux entering the cone is