The speed of light in fiber optic cable is approximately 200,000 kilometers per second.
While the speed of light in a vacuum is a constant (approximately 299,792,458 meters per second or about 300,000 kilometers per second), light slows down when it travels through other media like glass or plastic, which are the primary components of fiber optic cables. This reduction in speed is due to the interaction of light with the atoms in the material.
Here's a breakdown of factors affecting the speed of light in fiber:
- Index of Refraction: The index of refraction of a material determines how much light slows down. A higher index of refraction means a slower speed of light. Fiber optic cables have an index of refraction greater than 1, hence the reduced speed.
- Material Composition: Different types of glass or plastic used in fiber optic cables can have slightly different indices of refraction, leading to variations in the exact speed of light.
- Wavelength of Light: The wavelength of light can also influence its speed through a medium, a phenomenon known as dispersion.
Therefore, while it is common to cite 200,000 km/s as a general approximation, the exact speed can vary based on these specific properties of the fiber optic cable being used. This is an average speed accounting for the refractive index of the materials involved. In essence, the actual speed is roughly 67% of the speed of light in a vacuum.
