The index of refraction tells us the speed.
Air’s refractive index is about 1.0003, while water’s is about 1.3.
This means that light is “slower” in water than air.
How fast does light travel in air vs water?
Speed of Light in WaterThe speed of light in liquid is 225,000,000 meters per second (74,792,458 meters per second slower than c. Refraction index is caused by the molecules in a medium. Air has very spread out molecules which does spread out the light molecules when it makes contact which is why light travels slower.
Is light faster in air or water?
Light travels Faster in air, but slower in glass.In different materials, the speed of light slows down to less than c. In water, the refractive index is 1.3 and in glass, it is 1.5. Therefore, light travels faster through water, than it travels through glass.
What does light travel through the fastest?
Light travels at approximately 300,000 kilometers per second in a vacuum, which has a refractive index of 1.0, but it slows down to 225,000 kilometers per second in water (refractive index = 1.3) and 200,000 kilometers per second in glass (refractive index of 1.5). Speed of light is the lowest in diamonds.