When light waves pass from air to glass, the variables affected are the wavelength and velocity of the light.

The frequency of the light wave remains constant when it passes from one medium to another. The frequency represents the number of wave cycles that pass a given point per unit of time and is determined by the source of the light. Therefore, the frequency of the light does not change as it transitions from air to glass.

However, the wavelength and velocity of the light wave do change. The wavelength is the distance between two consecutive peaks or troughs of the wave. When light passes from air to glass, its wavelength decreases. This phenomenon is known as wavelength compression. The change in wavelength is due to the change in the refractive index of the two mediums.

Additionally, the velocity of light is also affected by the change in medium. In general, light travels slower in glass compared to air. This change in velocity is related to the refractive index of the glass, which is a measure of how much the speed of light is reduced when passing through the material.

Therefore, when light waves pass from air to glass, the variables affected are the wavelength and velocity of the light.