The three media commonly considered are vacuum, air, and glass. The ranking from fastest to slowest speed of light in these media is as follows:
Vacuum: Light travels at its maximum speed in a vacuum, which is approximately 299,792,458 meters per second (or about 299,792 kilometers per second). In a vacuum, there are no particles or atoms to interact with the photons, allowing them to move uninhibited.
Air: Light travels slightly slower in air compared to vacuum. The speed of light in air is very close to its speed in a vacuum but is slightly reduced due to the presence of molecules in the air. The exact speed of light in air depends on factors such as temperature and humidity but is typically around 299,702,547 meters per second.
Glass: Light travels slower in glass compared to both vacuum and air. The speed of light in glass varies depending on the type of glass and its refractive index, which determines how much the speed of light is reduced. In general, the speed of light in glass can range from about 200,000,000 to 225,000,000 meters per second.
The ranking is based on the properties of these media and their effect on the speed of light. Vacuum allows for the fastest propagation of light as there are no particles to interact with, while air and glass introduce more interactions and thus slow down the speed of light.