An infinite line charge is at the axis of a cylinder of length $1 \mathrm{m}$ and radius $7 \mathrm{cm}.$ If electric field at any point on the curved surface of cylinder is $250 \mathrm{N} {\mathrm{C}}^{-1}$, then, net electric flux through the cylinder is

A small conducting sphere is hanged by an insulating thread between the plates of a parallel plate capacitor as shown in figure. The net force on the sphere is

An electric dipole consists of two opposite charges, each of magnitude $1.0 \mathrm{\mu C}$ separated by a distance of $2.0 \mathrm{cm}$. The dipole is placed in an external electric field of ${10}^5 \mathrm{N} {\mathrm{C}}^{-1}$. The maximum torque on the dipole is