The speed of light in a vacuum is approximately 299,792,458 meters per second. However, light travels at a slower speed in water due to the refractive index of water. The refractive index of water is approximately 1.33. To calculate the speed of light in water, we can multiply the speed of light in a vacuum by the refractive index of water:
Speed of light in water = Speed of light in vacuum / Refractive index of water
Speed of light in water = 299,792,458 m/s / 1.33
Speed of light in water = 225,143,995.5 m/s
To calculate how long it takes for light to travel 2.5 meters in water, we can use the formula:
Time = Distance / Speed
Time = 2.5 m / 225,143,995.5 m/s
Time = 1.11 x 10^-8 seconds
Therefore, it takes approximately 1.11 x 10^-8 seconds for light to travel 2.5 meters in water.