Amplitude and medium are important issues of light waves and have not been discussed in the past.We measured them with three optics experiments.The first experiment shows that the polarization direction of small angle reflected light on metal remains unchanged.Liquid refractive index data prove that the light wave is a transverse wave on a one-dimensional string and the medium of the light wave is present.The second experiment measures the selection effect of the surface electrons on the amplitudeof light.The amplitude of light is obtained from the new refractive index formula.The third experimenton interference shows that solids can reduce the speed of light outside the surface. All three experiments demonstrate that the Substance density distribution of the electron is accurate.