A $2\,\mu F$ capacitor is charged as shown in the figure. The percentage of its stored energy dissipated after the switch $S$ is turned to position $2$, is.....$\%$

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

Two spherical conductors $A$ and $B$ of radii $1\, mm$ and $2\, mm$ are separated by  a distance of $5\, cm$ and are uniformly charged. If the spheres are connected by a  conducting wire then in equilibrium condition, the ratio of the magnitude of the electric  fields at the surfaces of spheres $A$ and $B$ is-

A point charge $'q'$ is placed at a point inside a hollow conducting sphere. Which of the  following electric force pattern is correct ?

In a particle accelerator, a current of $500 \,\mu A$ is carried by a proton beam in which each proton has a speed of $3 \times 10^7 \,m / s$. The cross-sectional area of the beam is $1.50 \,mm ^2$. The charge density in this beam (in $C / m ^3$ ) is close to

The electric flux from a cube of edge $l$ is $\phi $. If an edge of the cube is made $2l$ and the charge enclosed is halved, its value will be