Two spherical conductors $A$ and $B$ of radii $1\ mm$ and $2\ mm$ are separated by a distance of $5\ cm$ and are uniformly charged. If the spheres are connected by a conducting wire then in equilibrium condition, the ratio of the magnitude of the electric fields at the surfaces of spheres $A$ and $B$ is
$4 : 1$
$1:2$
$2:1$
$1:4$
An empty thick conducting shell of inner radius $a$ and outer radius $b$ is shown in figure.If it is observed that the inner face of the shell carries a uniform charge density $-\sigma$ and the surface carries a uniform charge density $ '\sigma '$
If the inner surface of the shell is earthed, then identify the correct statement(s)
Two concentric hollow conducting spheres of radius $r$ and $R$ are shown. The charge on outer shell is $Q$. What charge should be given to inner sphere so that the potential at any point $P$ outside the outer sphere is zero?
A metallic rod is placed in a uniform electric field. Select the correct option.
As shown in the figure, a point charge $Q$ is placed at the centre of conducting spherical shell of inner radius a and outer radius $b$. The electric field due to charge $Q$ in three different regions I, II and III is given by: $( I : r < a , II : a < r < b , III : r > b )$
$(a)$ A conductor $A$ with a cavity as shown in Figure $(a)$ is given a charge $Q$. Show that the entire charge must appear on the outer surface of the conductor.
$(b)$ Another conductor $B$ with charge $q$ is inserted into the cavity keeping $B$ insulated from $A$. Show that the total charge on the outside surface of $A \text { is } Q+q$ [Figure $(b)$]
$(c)\;A$ sensitive instrument is to be shielded from the strong electrostatic fields in its environment. Suggest a possible way.