The fig. shows lines of constant potential in a region in which an electric field is present. The value of the potential are written in brackets of the points $A, B$ and $C,$ the magnitude of the electric field is greatest at the point -

The figure shows a thick metallic sphere. If it is given a charge $+Q,$ then an electric field will be present in the region

An uncharged sphere of metal is placed in a uniform electric field produced by two large conducting parallel plates having equal and opposite charges, then lines of force look like

Figure shows a closed surface which intersects a conducting sphere. If a positive charge is placed at the point $P,$ the flux of the electric field through the closed surface

A charge $q$ is placed at the centre of a conducting spherical shell of radius $R,$ which is given a charge $Q.$ An external charge $Q\text{'}$ is also present at distance $R\text{'} \left(R\text{'}>R\right)$ from $q$. 
[ where $r$ is the distance of the point from $q$]