A sphere of radius $R$ and charge $Q$ is placed inside an imaginary sphere of radius $2R$ whose centre coincides with the given sphere. The flux related to imaginary sphere is
$\frac{Q}{{ \in _0}}$
$\frac{Q}{{2 \in _0}}$
$\frac{4Q}{{ \in _0}}$
$\frac{2Q}{{ \in _0}}$
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
Which graph shows variation of electric field of a uniformly charged sphere $w.r.t.$ distance $(r)$ from the centre
Three point charges $+q, -2q$ and $+q$ are placed at points $(x = 0, y = a, z = 0), (x = 0, y = 0,z = 0)$ and $(x = a, y = 0, z = 0)$ respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are
In an adjoining figure three capacitors $C_1,\,C_2$ and $C_3$ are joined to a battery. The correct condition will be (Symbols have their usual meanings)
In infinite long uniformly charged string is placed along $z-$ axis. Its linear charge density is $\lambda $. A point charge $q$ is moved from position $(a, 0, 0)$ to $(2a, 0, 0)$ then work done will be