What is a common cause of reduced signal quality on a fiber-optic transmission?

Dirt on the connector is a common cause of reduced signal quality in fiber-optic transmission because it can obstruct the light signal traveling through the fiber. Clean connections are crucial in fiber-optic systems since even a small amount of contamination can lead to significant signal loss or degradation. When the connector interface is dirty, the light may be absorbed or scattered, preventing an efficient transmission of data. This is why maintaining clean connectors is essential for ensuring optimal performance in fiber-optic networks.

The other factors mentioned, while contributing to signal quality issues, do not directly pertain to the cleanliness of the connector interfaces. For example, exceeding cable length can introduce attenuation that weakens the signal, cuts in the fiber can create breaks that entirely disrupt the transmission path, and improper bend radii can lead to signal loss due to excess bending. However, none of these directly involve contamination as seen with dirt on connectors.