Write value of Coulombian constant $k$ in $SI$ unit.

A $10\,\mu C$ charge is divided into two parts and placed at $1\,cm$ distance so that the repulsive force between them is maximum. The charges of the two parts are :

$(a)$ Explain the meaning of the statement ‘electric charge of a body is quantised’.

$(b)$ Why can one ignore quantisation of electric charge when dealing with macroscopic i.e., large scale charges?

Two identical positive charges $Q$ each are fixed at a distance of ' $2 a$ ' apart from each other. Another point charge qo with mass ' $m$ ' is placed at midpoint between two fixed charges. For a small displacement along the line joining the fixed charges, the charge $q_{0}$ executes $SHM$. The time period of oscillation of charge $q_{0}$ will be.

Two charged spheres separated at a distance $d$ exert a force $F$ on each other. If they are immersed in a liquid of dielectric constant $2$, then what is the force (if all conditions are same)

Identify the wrong statement in the following. Coulomb's law correctly describes the electric force that