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Question 1. Which physical principle allows light to be confined within the core of an optical fiber? A) Refraction B) Diffraction C) Total internal reflection D) Scattering Answer: C Explanation: Light is trapped in the core when it strikes the core‑cladding interface at an angle greater than the critical angle, causing total internal reflection. Question 2. The typical wavelength used for long‑haul fiber transmission to minimize attenuation is: A) 850 nm B) 1310 nm C) 1550 nm D) 1625 nm Answer: C Explanation: At 1550 nm, silica fiber exhibits its lowest loss (~0.2 dB/km), making it optimal for long distances. Question 3. In decibel calculations, a 3 dB increase in optical power corresponds to: A) Doubling the power B) Halving the power C) Increasing power by 10 % D) Decreasing power by 10 % Answer: A Explanation: A 3 dB rise represents a factor of 2 increase in linear power (10 log₁₀ 2 ≈ 3 dB). Question 4. Rayleigh scattering in fiber is primarily caused by:
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A) Micro‑bends in the fiber B) Density fluctuations at the molecular level C) Impurities in the glass D) Core‑cladding index mismatch Answer: B Explanation: Random variations in material density cause scattering of shorter‑wavelength light, known as Rayleigh scattering. Question 5. Chromatic dispersion in single‑mode fiber is mainly a result of: A) Different propagation speeds of modes B) Wavelength‑dependent refractive index C) Polarization differences D) Mechanical stress on the fiber Answer: B Explanation: The refractive index varies with wavelength, causing different spectral components to travel at slightly different speeds. Question 6. Which fiber type is specified by ITU‑T G.652? A) Bend‑insensitive single‑mode B) Standard single‑mode for 1550 nm C) Multimode OM D) Plastic optical fiber Answer: B Explanation: G.652 defines the characteristics of standard single‑mode fiber optimized for the 1310 nm and 1550 nm windows. Question 7. In a Passive Optical Network (PON), the device that terminates the fiber at the subscriber premises is called: A) OLT
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D) Higher split ratios without loss Answer: C Explanation: Centralized splitters aggregate many feeder fibers, decreasing the number of fibers that must reach the OLT. Question 11. When calculating an optical power budget, which parameter is NOT considered? A) Fiber attenuation (dB/km) B) Connector loss (dB) C) Transmitter wavelength drift (nm) D) Splice loss (dB) Answer: C Explanation: Power budget accounts for loss elements; wavelength drift affects dispersion but not the loss budget directly. Question 12. CWDM typically supports how many wavelength channels in the 1270–1610 nm range? A) 4 B) 8 C) 16 D) 32 Answer: B Explanation: CWDM uses 20 nm spacing, allowing up to 8 channels across the 1270–1610 nm window. Question 13. The primary benefit of using ribbon fiber in a cable is: A) Higher tensile strength B) Simplified mass splicing and termination C) Better bend resistance D) Lower cost per meter
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Answer: B Explanation: Ribbon fiber aligns multiple fibers in a flat plane, enabling simultaneous splicing and reducing termination time. Question 14. Which cable type is most suitable for aerial deployment with minimal support structures? A) Loose‑tube armored cable B) ADSS (All‑Dielectric Self‑Supporting) cable C) Tight‑buffered indoor cable D) Ribbon‑fiber cable Answer: B Explanation: ADSS cables are designed to support their own weight on poles without metal armoring. Question 15. The recommended minimum bend radius for a standard 9/125 μm single‑mode fiber is: A) 5 mm B) 10 mm C) 30 mm D) 60 mm Answer: C Explanation: A 30 mm (≈10× fiber diameter) bend radius avoids excess macro‑bending loss in standard SMF. Question 16. In underground fiber installation, a micro‑trench typically has a depth of: A) 5 cm B) 10 cm C) 30 cm D) 60 cm
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Explanation: Core‑alignment splicers employ cameras and image processing to align fiber cores before the fusion arc. Question 20. A mechanical splice typically introduces an insertion loss of about: A) ≤0.1 dB B) 0.2–0.5 dB C) 1–2 dB D) >3 dB Answer: C Explanation: Mechanical splices are less efficient than fusion splices, usually causing 1–2 dB loss. Question 21. Which connector polishing type provides the lowest back‑reflection? A) PC (Physical Contact) B) UPC (Ultra Physical Contact) C) APC (Angled Physical Contact) D) FC/PC Answer: C Explanation: APC connectors have an 8° angle on the end face, reducing return loss to ≤‑ 55 dB. Question 22. The standard connector used for high‑density data center applications is: A) SC B) LC C) ST D) E Answer: B Explanation: LC connectors are small, latch‑type, and widely adopted for high‑port‑density environments.
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Question 23. An OTDR trace that shows a sudden increase in loss followed by a flat line most likely indicates: A) A fiber break (cut) B) A high‑loss connector C) A splice with high loss D) A macro‑bend event Answer: A Explanation: A sharp loss followed by no reflected signal is characteristic of a fiber cut. Question 24. Optical Return Loss (ORL) specifications are most critical for which type of network element? A) Passive splitters B) Optical amplifiers C) Transceivers with coherent detection D) Fiber patch panels Answer: C Explanation: Coherent receivers are highly sensitive to reflected light; low ORL is required to prevent laser instability. Question 25. When verifying a newly installed FTTH link, the ONT receives an optical power of – 28 dBm while the receiver sensitivity is – 28 dBm. The link is: A) Over‑powered B) Under‑powered C) Exactly at the limit, acceptable but no margin D) Faulty, needs repair Answer: C Explanation: The received power meets the sensitivity threshold, leaving zero power margin.
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B) TIA/EIA‑ 568
C) ISO/IEC 11801
D) IEEE 802.3bz Answer: B Explanation: TIA/EIA‑568 specifies structured cabling requirements for commercial premises in the U.S. Question 30. The National Electrical Safety Code (NESC) primarily addresses: A) Data protocol standards B) Safety of electric power and communication lines C) Fiber optic connector specifications D) Environmental impact assessments Answer: B Explanation: NESC provides safety rules for the installation and maintenance of electric and communication utilities. Question 31. Which loss component is generally highest in a typical indoor fiber link? A) Fiber attenuation per km B) Connector loss C) Splice loss D) Bending loss Answer: B Explanation: Indoor links often have many connectors; each contributes ~0.3 dB, dominating total loss for short runs. Question 32. A fiber with a core diameter of 50 μm and a cladding of 125 μm is classified as: A) Single‑mode B) Multimode OM C) Multimode OM
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D) Plastic optical fiber Answer: B Explanation: 50 μm core multimode fibers correspond to OM1 (or OM2) categories, depending on bandwidth. Question 33. Polarization Mode Dispersion (PMD) becomes a limiting factor primarily at: A) Short distances (<1 km) B) High data rates (>10 Gbps) over long distances C) Low‑temperature environments D) Multimode operation Answer: B Explanation: PMD causes differential group delay that degrades high‑speed signals over long spans. Question 34. In a fiber‑to‑the‑curb (FTTC) deployment, the last‑mile connection to the home is typically: A) Copper coaxial cable B) Fiber optic cable C) Wireless link D) Power‑line communication Answer: A Explanation: FTTC brings fiber to a curbside cabinet, then uses existing copper (e.g., VDSL) for the final connection. Question 35. The term “macro‑bend loss” refers to loss caused by: A) Microscopic imperfections in the glass B) Bends with radii comparable to the fiber diameter C) Bends with radii much larger than the fiber diameter but still inducing mode leakage D) Thermal expansion of the fiber coating
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Explanation: 100 GHz corresponds to about 0.8 nm at 1550 nm (Δλ ≈ λ²·Δf / c). Question 39. Which type of fiber optic cable is most resistant to rodents? A) Loose‑tube aerial cable B) Armored steel‑wire cable C) Tight‑buffered indoor cable D) Ribbon fiber cable Answer: B Explanation: Armored cables include a steel wire layer that deters rodent damage. Question 40. The “attenuation coefficient” of a fiber is expressed in: A) dB/km B) dBm C) Hz D) μm Answer: A Explanation: Attenuation coefficient quantifies loss per unit length, typically in decibels per kilometer. Question 41. Which of the following connectors is most commonly used in legacy telecom installations for multimode fiber? A) LC B) SC C) ST D) MPO Answer: C Explanation: ST (bayonet) connectors were widely used in older multimode plant installations.
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Question 42. In a fiber link, the “receiver sensitivity” is defined as: A) Minimum optical power required for error‑free operation B) Maximum power the receiver can handle without damage C) The wavelength at which the receiver operates best D) The bandwidth of the receiver circuitry Answer: A Explanation: Sensitivity indicates the lowest input power that still yields acceptable bit error rate. Question 43. Which of the following best describes the purpose of a “patch panel” in a fiber distribution hub? A) To amplify signals B) To provide a neat, organized termination point for fiber pigtails and facilitate cross‑connections C) To convert optical signals to electrical signals D) To monitor temperature and humidity Answer: B Explanation: Patch panels enable flexible routing and easy management of fiber connections. Question 44. The term “bend‑insensitive” fiber refers to a fiber that: A) Has a larger core diameter to reduce loss B) Uses a special coating and refractive index profile to limit macro‑bend loss C) Is made of polymer rather than glass D) Is only used in indoor applications Answer: B Explanation: Bend‑insensitive fibers (e.g., G.657) incorporate a trench‑type index profile and robust coating to tolerate tight bends. Question 45. A Visual Fault Locator (VFL) is primarily used to: A) Measure absolute loss in dB
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D. Excessive splice heat causing micro‑cracks Answer: B Explanation: Index‑matching gel reduces Fresnel reflections; it does not increase attenuation. Question 49. The IEC standard that defines the safety classification of lasers is: A) IEC 60825‑ 1 B. IEC 61000‑ 4 ‑ 2 C. IEC 61753‑ 1 D. IEC 61508 Answer: A Explanation: IEC 60825‑1 specifies laser hazard classes and safety requirements. Question 50. In a fiber optic cable, the “tight‑buffered” design is advantageous because: A) It allows higher tensile strength for aerial deployment B) It simplifies field termination without the need for a jacketed tube C) It provides superior resistance to water ingress D) It supports higher data rates than loose‑tube designs Answer: B Explanation: Tight‑buffered fibers have a protective polymer coating directly on the fiber, enabling easier connectorization. Question 51. Which of the following is the most common cause of “no‑light” alarms in an ONT? A. Connector contamination B. Fiber cut or break C. Excessive splice loss D. Temperature drift in the transmitter Answer: B Explanation: A complete loss of signal indicates a physical discontinuity such as a cut.
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Question 52. The term “OTDR dynamic range” refers to: A. The maximum distance the OTDR can accurately measure loss B. The wavelength range the OTDR can emit C. The number of pulses per second the OTDR can generate D. The input power the OTDR can tolerate Answer: A Explanation: Dynamic range is the difference between the highest measurable loss and the noise floor, determining the longest measurable fiber length. Question 53. Which of the following best describes a “splitter loss” in a PON? A. The loss caused by attenuation in the fiber core B. The insertion loss introduced by the splitter device itself, typically 0.5–1 dB per split C. The loss due to connector polishing defects D. The loss caused by modal dispersion Answer: B Explanation: Splitters introduce a fixed insertion loss per split ratio, independent of fiber attenuation. Question 54. A fiber with an NA (numerical aperture) of 0.22 will have a larger acceptance angle than a fiber with NA 0.12. This means: A. It can couple more light from a source, reducing connector loss B. It suffers higher attenuation per km C. It is more bend‑sensitive D. It supports only single‑mode propagation Answer: A Explanation: Higher NA allows a wider range of incident angles, improving coupling efficiency. Question 55. The primary purpose of a “fiber distribution hub” (FDH) is to:
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B. A splice with high loss C. Fresnel reflection from a connector or termination D. Bending loss Answer: C Explanation: Reflections at connectors generate secondary peaks (“ghosts”) on the trace. Question 59. In a fiber optic system, “chromatic dispersion compensation” is typically achieved using: A. Dispersion‑compensating fiber (DCF) B. Higher launch power C. Larger core diameter fibers D. Increasing splice count Answer: A Explanation: DCF has opposite dispersion characteristics, offsetting accumulated chromatic dispersion. Question 60. Which of the following is NOT a typical component of a fiber‑to‑the‑home (FTTH) customer premise equipment? A. ONT (Optical Network Terminal) B. Power supply (DC) C. Ethernet switch D. Optical Amplifier (EDFA) Answer: D Explanation: EDFAs are used in long‑haul links, not in the customer‑side ONT. Question 61. The primary advantage of using a “centralized” splitter over a “distributed” splitter in a PON is: A. Lower insertion loss per split B. Reduced fiber count in the feeder plant
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C. Easier field access for maintenance D. Higher split ratios without penalty Answer: B Explanation: Centralized splitters aggregate many feeder fibers, minimizing the number of fibers that need to reach the OLT. Question 62. In a fiber optic cable, “armoring” is primarily used to: A. Improve optical performance B. Provide mechanical protection against crushing and rodent attacks C. Reduce microbending loss D. Increase bandwidth Answer: B Explanation: Armored cables have steel or aluminum layers that protect against physical damage. Question 63. The term “micro‑bending loss” is most closely associated with: A. Bends larger than the cable’s minimum bend radius B. Small irregularities or pressure on the fiber coating causing mode coupling C. Bends caused by wind‑induced sway of aerial cables D. Bends at splice points only Answer: B Explanation: Micro‑bends are tiny deformations that induce scattering and loss. Question 64. Which of the following is a key parameter when selecting an optical transceiver for a 10 Gbps Ethernet link? A. Wavelength (e.g., 850 nm vs. 1310 nm) B. Connector type only C. Cable color D. Number of fibers in the cable
