Prove that velocity of propagation in a concentric underground cable is equal to the speed of light •

Prove that velocity of propagation in a concentric underground cable is equal to the speed of light

Absolute permittivity of a medium
μ = Absolute permeability of a medium
E = EoEr and μ =μoμr
Eo = Absolute permittivity of free space and Er = relative absolute permittivity
μo = Absolute permeability of free space and μr = relative absolute permeability
For magnetic material V = √(1/LC)
V = √[1/(μo/2π • inB/A × 2πEo