Final answer:
The cladding provides a lower refractive index than the core in fiber optics, ensuring total internal reflection and preventing signal loss.
Step-by-step explanation:
The part of the fiber that provides a lower refractive index than the core to ensure total internal reflection is known as the cladding. The cladding surrounds the fibers in bundles and prevents light from being transmitted between the fibers, allowing most of the light to be guided along the fiber.
Without cladding, light could pass between fibers in contact with each other. The cladding is essential because it lowers the chances of signal loss and ensures that the fiber optics can transmit a quality image to the other end. Additionally, cladding, combined with an additional protective layer, grants the optical fibers durability and flexibility.