When light enters from air to glass, the only change that occurs is the velocity of light. The other properties of light, such as wavelength, frequency, and amplitude, remain the same.

Explanation:
- Velocity of light: The speed of light changes when it enters a different medium, such as glass. In air, the speed of light is approximately 3 x 10^8 meters per second. However, when light enters glass, its speed decreases to around 2 x 10^8 meters per second. This change in velocity is due to the difference in the refractive index of air and glass. The refractive index is a measure of how much a medium can bend or refract light.
- Wavelength: The wavelength of light does not change when it enters a different medium. Wavelength is the distance between two consecutive peaks or troughs of a wave. It is determined by the source of light and remains constant regardless of the medium it travels through.
- Frequency: Like the wavelength, the frequency of light also remains the same when it enters a different medium. Frequency is the number of wave cycles that pass a fixed point in one second and is determined by the source of light. It does not change when light enters a different medium.
- Amplitude: The amplitude of light refers to the height or intensity of the wave. It does not change when light enters a different medium. The amplitude is determined by the source of light and remains constant regardless of the medium it travels through.

To summarize, when light enters from air to glass, the only change that occurs is the velocity of light. The wavelength, frequency, and amplitude of light remain the same.