Final answer:
The statement about multitasking is false; multitasking refers to the ability of a processor to handle multiple tasks, not to the division of communication circuits. Refraction is useful in fiber optic cables because it allows light to be guided with minimal signal loss.
Step-by-step explanation:
The statement "Multitasking means to break one high-speed physical communication circuit into several lower-speed logical circuits so that different devices can simultaneously use it." is false. Multitasking generally refers to the ability of a processor to handle multiple tasks (or processes) at the same time. The process of breaking a single high-speed physical communication circuit into several lower-speed logical circuits for simultaneous use by different devices is known as time-division multiplexing (TDM).
Regarding the questions provided for reference:
- Refraction is indeed useful in fiber optic cables for transmitting signals, making the statement true. Refraction is the bending of light as it passes from one medium to another, which is a principle that allows fiber optic cables to guide light with minimal loss of signal.
- All people do not have the same proportion of slow-twitch to fast-twitch muscle fibers, so that statement would be false. The proportion of these fibers can vary greatly among individuals and can be influenced by genetics as well as training.