A thin spherical conducting shell of radius $R$ has a charge $q.$ Another charge $Q$ is placed at the centre of the shell. The electrostatic potential at a point $p$ a distance $R/2$ from the centre of the shell is
$\frac{{\left( {q + Q} \right)2}}{{4\pi { \in _0}R}}$
$\frac{{2Q}}{{4\pi { \in _0}R}}$
$\frac{{2Q}}{{4\pi { \in _0}R}} - \frac{{2q}}{{4\pi { \in _0}R}}$
$\frac{{2Q}}{{4\pi { \in _0}R}} + \frac{{q}}{{4\pi { \in _0}R}}$
A charge $q$ is placed at the centre of the line joining two equal charges $Q$. The system of the three charges will be in equilibrium, if $q$ is equal to
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 horizontal electric field $E =$
Electric charges $q, q, -2\,q$ are placed at the comers of an equilateral triangle $ABC$ of side $l$. The magnitude of electric dipole moment of the system is
If potential at centre of uniformaly charged ring is $V_0$ then electric field at its centre will be (assume radius $=R$ )
A hollow insulated conduction sphere is given a positive charge of $10\,\mu C$. What will be the electric field at the centre of the sphere if its radius is $2\,m$ ?................$\mu Cm^{-2}$