The electric field intensity at a point in vacuum is equal to

A charged water drop whose radius is $0.1\,\mu m$ is in equilibrium in an electric field. If charge on it is equal to charge of an electron, then intensity of electric field will be.......$N/C$ $(g = 10\,m{s^{ - 1}})$

For what type of charge distribution, electric field can be obtained by using Coulomb’s law and superposition principle ?

A flat circular disc has a charge $ + Q$ uniformly distributed on the disc. A charge $ + q$ is thrown with kinetic energy $E$ towards the disc along its normal axis. The charge $q$ will

The electric field in a region is radially outward and at a point is given by $E=250 \,r V / m$ (where $r$ is the distance of the point from origin). Calculate the charge contained in a sphere of radius $20 \,cm$ centred at the origin ......... $C$

Two equal negative charges $-\, q$ each are fixed at the points $(0, a)$ and $(0, -a)$ on the $Y$ -axis. A positive charge $Q$ is released from rest at the point $(2a, 0)$ on the $X$ -axis. The charge $Q$ will :-