What is $k$ in Electrostatic Force?

Hint: The collaboration between the charged objects is a non-contact force that acts on the distance of separation, charge, and distance. All electrical relations include a force that shows the importance of these three variables. The measurable expression that comes as a result of these three variables on electric force is known as Coulomb's law. Hence
we can describe K from this expression.

Complete answer:
We can state Coulomb’s law as “The electrical force in effect between two charged bodies is directly proportional to the product of the quantity of charge on the bodies and it is inversely proportional to the square of the parting distance between them”. In equation form, Coulomb's law can be denoted as
$F = \dfrac{{k \times {Q_1} \times {Q_2}}}{{{d^2}}}$
Where Q1 denotes the quantity of charge on object 1 (in Coulombs), Q2 denotes the quantity of charge on object 2 (in Coulombs), and d denotes the distance of partition between the two objects (in meters). The symbol k or K is a proportionality constant known as the Coulomb's law constant or electrostatic force constant. The value of the constant is reliant on the medium that the charged objects are submerged in. In the case of air, the value is about \[9.0 \times {10^9}\;N{m^2}{C^{ - 2}}\]. If the charged objects are present in water, the value of $k$ the can is decreased by as much as a factor of \[80\] . It is useful to point out that the units on k when it is replaced into the equation, the units on charge (Coulombs), and the units of distance (meters) will be canceled out, which leaves a \[N\] as the unit of force.

Note:
The Coulomb's law equation provides an accurate description of the force between two objects whenever the objects act as point charges. A charged conducting sphere unites with other charged objects as though all of its charges were positioned at its center. Though the charge is uniformly spread across the surface of the sphere, the center of charge can be taken as the center of the sphere. The sphere acts as a point charge with its excess charge located at its center. As Coulomb's law applies to point charges, the distance d in the equation is the distance between the centers of the charge for both the objects and not the distance between their closest surfaces.