Question

What is the value of k as used in Coulomb's law?

Answer 1

k is the Coulomb's constant, which is equal to $8.988\times {10}^{9}N{m}^2/C^2$.
It is given by $k=\frac{1}{4\pi {\epsilon }_0}$.
where ${\epsilon }_0$ is the electric constant, also called the permittivity of the vacuum.