Final answer:
Refraction is indeed vital in fiber optic cables, as it enables light to be transmitted over long distances with minimal loss, high bandwidth, and reduced crosstalk through the principle of total internal reflection.
Step-by-step explanation:
The statement that refraction is useful in fiber optic cables for transmitting signals is true. Refraction is a phenomen where a wave changes its speed as it passes from one medium to another, resulting in a change in direction. In fiber optics, light is transmitted down plastic or glass fibers using a principle called total internal reflection.
When light enters the fiber at an angle greater than the critical angle relative to the interface between materials with different refractive indexes, it reflects completely inside the cable and can travel long distances with low loss. This allows for the transmission of signals such as telephone, internet, and cable TV with high bandwidth and reduced crosstalk.