Charges are uniformly spread on the surface of a conducting sphere. The electric field from the centre of the sphere to a point outside the sphere varies with distance $r$ from the centre as:

If $q$ is the charge per unit area on the surface of a conductor,then the electric field intensity at a point on the surface is

$A$ charge $q$ is placed at one corner of a cube. The electric flux through any of the three faces adjacent to the charge is zero. The flux through any one of the other three faces is

Obtain the expression for the electric field due to:
$(i)$ An infinite plane sheet with uniform charge distribution.
$(ii)$ $A$ thin spherical shell with uniform charge distribution at a point outside it.
$(iii)$ $A$ thin spherical shell with uniform charge distribution at a point inside it.

Two parallel large thin metal sheets have equal surface charge densities $(\sigma = 26.4 \times 10^{-12} \, C/m^2)$ of opposite signs. The electric field between these sheets is

The magnitude of electric field on the surface of a uniformly charged metallic spherical shell is $E$. If a hole is made in it using an insulating device,then the magnitude of electric field in the hole will be