What is the constant used in coulomb's law?

Answer 1

In the MKS system of units, the proportionality constant in Coulomb's law is 1/( 4 pi �µ0 )

' �µ0 ' is the electrostatic permittivity of free space.

It does seem unnecessarily complicated. But there are reasons for it, and it all works out.

Answer2:

The constant used in Coulomb's law is one of the most important constants in Physics. It is related to Planck,s Constant, h. The permittivity e0= 1/zc where c is the speed of light and z is the free space impedance, z= w/q ; w is the quantum magnetic charge in webers ,volt-second and q is the quantum electric charge q. Planck's Constant h= qw = 2/3 E-33 and z = 375 ohms.= w/q

The q= 4/3 E-18 Coulomb and w = 500 E-18 volt second.

The quantum electric charge q=4/3 E-18 C x 6.25E18e/C= 25/3 e = (13U1d) in Quarks., U=Up and d=down.

The electron is an rms charge F= -e^2/4pi e0 r^2 = - e^2zc/22pir^2=e^2hc/2q^22pir^2= -alpha ch/2pir^2.

The Fine Structure Constant alpha = 0 .5 (e/q)^2 = .5( .16/4/3) = .5 (.12)^2 = .5 (.0144) = 7.2E-3

F = -ach/2pi r^2 = -vp/r where v=ac = 7.2E-3 300Mm/s = 2.16Mm/s.