dalehileman wrote: Quote:
the permittivity (capacitance per unit volume) and permeability to a magnetic field.
I am wondering however, Con, whether either of these values might be set using the velocity of light c itself as a determinant
They can be derived independently (this is the whole point!); They arose from the work of researchers into electricity and magnetism mainly in the 19th century.
In 1851 Hippolyte Fizeau developed a method to determine the speed of light based on time-of-flight measurements on Earth and reported a value of 315000 km/s. His method was later improved upon by Léon Foucault who obtained a value of 298000 km/s.
In 1856, Wilhelm Eduard Weber and Rudolf Kohlrausch measured the ratio of the electromagnetic and electrostatic units of charge, 1/√ε0μ0, by discharging a Leyden jar, and found that its numerical value was very close to the speed of light as measured directly by Fizeau.
In 1857 Gustav Kirchhoff calculated that an electric signal in a resistanceless wire travels along the wire at this speed.
In 1862 James Clerk Maxwell (one of the giants of science) showed that, according to the theory of electromagnetism he was working on, what he called 'electromagnetic waves' propagate in empty space at a speed equal to the Weber/Kohrausch ratio, and drawing attention to the numerical proximity of this value to the speed of light as measured by Fizeau, he proposed that light is in fact an electromagnetic wave. These were later verified to exist and put to practical use (radio, lasers, etc).