Why do light and sound travel at different speeds?
The forms of waves that make up light (electricity and magnetism) and sound/acoustics (pressure and displacement/velocity) are different. They are governed by different physical equations – Maxwell’s equations for EM and two equations without as great of names for acoustics. These equations depend on different physical parameters of a medium. Given the two wave equations for any type of wave you can derive a relation describing wave velocity using (typically) frequency and the physical parameters of the medium. The electromagnetic speed (typically phase velocity) depends on the permittivity and permeability of a medium, while the acoustic speed depends on the density and modulus of elasticity. So the speeds of the two waves depend on different physical parameters of a medium. FYI, the forms of equations for speed are: c=1/sqrt(mu*epsilon) for electromagnetics c=sqrt(lambda/rho) for acoustics Where mu = permeability, epsilon = permittivity, lambda = modulus of elasticity, and rho = dens
