This set of Optical Communications Multiple Choice Questions & Answers (MCQs) focuses on “Cable Design”.
1. The cable must be designed such that the strain on the fiber in the cable does not exceed__________
Explanation: The constraints included in cable design are stability, protection, strength and jointing of the fibers. The fiber cable does not get affected if the strain exerted on it is below 0.2%. Although, it is suggested that the permanent strain on the fiber should be less than 0.1%.
2. How many categories exists in case of cable design?
Explanation: Cable design is separated into three categories. They are fiber buffering, cable structural and strength and cable sheath and water barrier. After successfully going through these tests, an optical cable is designed.
3. How many types of buffer jackets are used in fiber buffering?
Explanation: The buffer jacket is designed to protect the fiber from micro-bending losses. There are three types of buffer jackets used in fiber buffering. They are tight buffer jackets, loose tube buffer jackets and filled loose tube buffer jacket.
4. Loose tube buffer jackets exhibits a low resistance to movement of the fiber. State whether the given statement is true or false.
Explanation: Loose tube buffering is achieved by using a hard, smooth, flexible material in the form of extruded tube. The buffer tube is smooth from inside. Thus, it exhibits a low resistance to movement of the fiber. Also, it can be easily stripped for jointing or fiber termination.
5. An inclusion of one or more structural members in an optical fiber so as to serve as a cable core foundation around which the buffer fibers may be wrapped is called _____________
Explanation: Optical fiber is made structurally stronger by adding one or more strength members. The core fiber is trapped with buffered fibers or they are slotted in the core foundation. This approach is called as stranding.
6. Which of the following is not a strength member used in optical cable?
a) Steel wire
c) Aramid yarns
d) Glass elements
Explanation: Strength members or tensile members are added to the fiber to make it stronger and durable. These members include solid steel wire, dielectric aramid yarns (Kevlar), glass elements etc. Germanium is not a structural or strength member.
7. When the stranding approach consists of individual elements (e.g. single-fiber or multi fiber loose tube buffer) than the cable is termed as
a) Optical unit cable
b) Coaxial cable
c) Layer cable
d) Bare glass cable
Explanation: The stranding approach consists of a fiber core foundation around which the buffered fibers are wrapped. The cable elements are stranded in one, two or several layers around the central structural member. When the stranding is composed of individual elements, then the cable is termed as layer cable. If the cable core consists of stranding elements each of which comprises a unit of stranding elements, then it is termed as optical unit cable.
8. The primary function of the structural member is load bearing. State whether the given statement is true or false.
Explanation: The primary function of the structural member is not load bearing. It’s function is to provide suitable accommodation for the fiber ribbons within the cables. These fiber ribbons lie in the helical grooves or slots formed in the surface of the structural members.
9. What is the Young’s modulus of Kevlar, an aromatic polyester?
a) 9 ×1010Nm-2
b) 10 ×1010Nm-2
c) 12 ×1010Nm-2
d) 13 ×1010Nm-2
Explanation: Kevlar is used as a strength member in an optical fiber. The Young’s modulus of Kevlar is very high which gives it strength to weight ratio advantage four times that of steel. Kevlar is coated with extruded plastic to provide a smooth surface which in turn prevents micro-bending losses.
10. The cable is normally covered with an outer plastic sheath to reduce _______________
Explanation: Abrasion is the process of scraping or wearing something away. If the cable is not coated with plastic sheath, it gives rise to effects such as abrasion and crushing. The most common plastic sheath material used in covering a cable is polyethylene (PE).
Sanfoundry Global Education & Learning Series – Optical Communications.
To practice all areas of Optical Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.