Final answer:
The '62.5' in '62.5/125 fiber' refers to the diameter of the fiber optic core in micrometers, indicating multi-mode capability with a cladding diameter of 125µm.
Step-by-step explanation:
When we say "62.5/125 fiber", the term "62.5" refers to the diameter of the fiber optic core, which is the pathway that transmits light signals. The core diameter is measured in micrometers (µm). In this case, 62.5µm is considered a multi-mode fiber, which means it can carry multiple light modes or signals at the same time. The number "125" typically follows and represents the diameter of the cladding, which is a layer of glass around the core that reflects light back into the core to improve signal strength.