Angle between equipotential surface and lines of force is.......$^o$

In the circuit shown in the figure, the potential difference across the $4.5\,\,\mu F$ capacitor is.......$volts$

Capacity of an isolated sphere is increased $n$ times when it is enclosed by an earthed concentric sphere. The ratio of their radii is

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 $2\,m$ ?................$\mu Cm^{-2}$

In the circuit, shown in the figure, the effective capacitance between $A$ and $B$ is......$\mu F$

Charge of $2Q$ and $-Q$ are placed on two plates of a parallel plate capacitor if capacitance of capacitor is $C$ find potential difference between the plates