Cisco CCNA mock exam questions sample test – Question 73

.Which cable can suffer attenuation if it is bent beyond the minimum bend radius?

C. Co-axial
D. Fiber optic

Correct Answer: D

Fiber-optic cables can suffer attenuation if they are bent beyond the minimum bend radius. Fiber-optic cables work on the principle of total internal reflection. The fiber optic cable uses
a laser and glass tubes with refractive internal coating to achieve total internal reflection. If a light ray travelling in the tube is bent at a certain angle, the light ray will be reflected inside
the medium instead of passing through the medium. If the fiber optic cables are bent beyond the minimum bend radius, the signal will be lost and the cable will suffer attenuation.
Fiber cables are expensive and are typically used for outdoor campus backbone. However, as the fiber cables use light to carry signals, they are not affected by the electro-magnetic
interference (EMI) generated by electric cables.
Another advantage of fiber optic cabling is its applicability to situations where electrical issues may exist in the environment. Even in situations where the length of the cable run is well
within the attenuation limits of STP (for example 55 meters), voltage differences between buildings can cause issues. That is a problem that can be solved by using fiber on the run,
which is not impacted by electrical issue.
All other cables typically use copper to carry low voltage signals and are not affected by normal bending. However, even copper cables may suffer some signal loss if there are bends
in the cable.
Network Fundamentals
Select the appropriate cabling type based on implementation requirements
Cisco > Articles > Network Technology > General Networking > Fiber-Optic Technologies