Two equal negative charges $-q$ are fixed at points $(0, -a)$ and $(0, a)$ in the $x-y$ plane. A positive charge $Q$ is released from rest at a point $(2a, 0)$. The charge $Q$ will

Electric field inside a uniformly charged sphere of radius $R,$ is ($r$ is distance from centre, $r < R$)

The plates of a parallel plate capacitor are charged up to $100\, volt$. A $2\, mm$ thick plate is inserted between the plates, then to maintain the same potential difference, the distance between the capacitor plates is increased by $1.6\, mm$. The dielectric constant of the plate is

Half of the space between parallel plate capacitor is filled with a medium of dielectric constant $K$ parallel to the plates . If initially the capacity is $C$, then the new capacity will be

If potential at centre of uniformaly charged ring is $V_0$ then electric field at its centre will be (assume radius $=R$ )

If the electric potential of the inner shell is $10\,V$ and that of the outer shell is $5\,V$ , then the potential at the centre will be.....$V$