Electric flux through surface $s_1$ :-
is minimum
is maximum
equal to $s_2$ but less than $s_4$
equal for all surfaces
A charge $q$ is placed at the centre of cubical box of side a with top open. The flux of the electric field through one of the surface of the cubical box is
Two spherical conductors $B$ and $C$ having equal radii and carrying equal charges in them repel each other with a force $F$ when kept apart at some some distance. $A$ third spherical conductor having same radius as that of $B$ but uncharged, is brought in contact with $B$, then brought in contact with $C$ and finally removed away from both. The new force of repulsion between $B$ and $C$ is-
Two similar tiny balls of mass $m$, each carrying charge $q$ are hung from silk thread of length $l$ as shown in Fig. These are separated by a distance $x$ and angle $2 \theta \sim 10$. Then for equilibrium :-
The four capacitors, each of $25\,\mu F$ are connected as shown in Fig. The $dc$ voltmeter reads $200\,V$. The charge on each plate of capacitor is
Figures below show regular hexagons, with charges at the vertices, In which of the following cases the electric field at the centre is not zero.