Speed of light dimensions of a capacitor, whereas the value of the vacuum permeability is fixed at exactly through the definition of the ampere. Rosa and Dorsey used this method in 1907 to find a value of . Another way to measure the speed of light is to independently measure the frequency "f" and wavelength "λ" of an electromagnetic wave in vacuum. The value of "c" can then be found by using the relation "c" = "fλ". One option is to measure the resonance frequency of a cavity resonator. If the dimensions of the resonance cavity are also known, these can be used
One-way speed of light verifiable two-way speed, whereas the one-way speed of light is allowed to take the form in opposite directions: κ can have values between 0 and 1. In the extreme as κ approaches 1, light might propagate in one direction instantaneously, provided it takes the entire round-trip time to travel in the opposite direction. Following Edwards and Winnie, Anderson "et al." formulated generalized Lorentz transformations for arbitrary boosts of the form: (with κ and κ' being the synchrony vectors in frames S and S', respectively). This transformation indicates the one-way speed of light is conventional in all frames, leaving the two-way