The speed of electromagnetic wave in vacuum

If c is the speed of electromagnetic waves in vacuum, its speed in a medium of dielectric K and relative permeability mu_(r) is

The speed of electmagnetic waves in vacuum is equal to

The speed of electromagnetic waves in air is

The speed of electromagnetic wave is same for

The speed of electromagnetic waves in free space is

Write the relation for the speed of electromagnetic wave in terms of the amplitudes of electric and magnetic fields.