A wheel having mass $m$ has charges $+q $ and $-q$ on diametrically opposite points. It remains in equilibrium on a rough inclined plane in the presence of uniform vertical electric field $E =$  

A parallel plate condenser has a uniform electric field $E(V/m)$ in the space between the plates. If the distance between the plates is $d(m)$ and area of each plate is $A(m^2)$, then the energy (joules) stored in the condenser is

Force between $A$ and $B$ is $F$. If $75\%$ charge of $A$ is transferred to $B$ then force between $A$ and $B$ is

If the electric flux entering and leaving an enclosed surface respectively is ${\phi _1}$ and  ${\phi _2}$ the electric charge inside the surface will be 

As shown in the fig. charges $+\,q$ and $-\,q$ are placed at the vertices $B$ and $C$ of an isosceles triangle. The potential at the vertex $A$ is

Two spherical conductors each of capacity $C$ are charged to potential $V$ and $-V$ . These are then connected by mean of a fine conducting wire. The loss of energy will be