What characteristic of light limits the length of fiber cables and increases with cable length?

The characteristic that limits the length of fiber cables and increases with cable length is attenuation. Attenuation refers to the loss of signal strength as light travels through the fiber optic cable. This loss occurs due to several factors, including absorption of light by the fiber material, scattering of light, and imperfections in the cable.

As the length of the fiber cable increases, the attenuation effect becomes more pronounced, resulting in a weaker signal at the receiving end. This is why fiber optic systems must be designed with a maximum length in mind, as excessive lengths can lead to unacceptable levels of signal loss.

While dispersion does play a role in how signals are transmitted within the fiber, it primarily affects the timing and width of the signal pulses rather than the overall power or strength of the light traveling through the fiber. In contrast, attenuation is a direct measure of the actual loss of signal strength over a given distance, making it the correct answer in this context.