CO Fiber Optics Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
A. Increase in optical signal strength
B. Loss of optical signal power over distance
C. Change in cable frequency
D. Heat generated by optical fibers
Rationale: Attenuation is the gradual reduction of signal power as light
travels through the fiber.
2. Which fiber type is commonly used for long-distance
telecommunications?
A. Multimode step-index
B. Multimode graded-index
C. Single-mode fiber
D. Plastic optical fiber
Rationale: Single-mode fiber allows long-distance transmission with
minimal dispersion.
3. The glass core of a single-mode fiber typically has a diameter of:
A. 100 µm
B. 62.5 µm
C. 8–10 µm
D. 125 µm
Rationale: Single-mode fiber cores are very small, around 8–10 microns.
,4. What is the purpose of cladding in an optical fiber?
A. Increase fiber strength
B. Provide electric insulation
C. Maintain total internal reflection
D. Produce light
Rationale: Cladding ensures the light stays confined in the core through
total internal reflection.
5. The primary cause of dispersion in multimode fiber is:
A. Chromatic dispersion
B. Modal dispersion
C. Thermal dispersion
D. Oscillation
Rationale: Multimode fibers carry multiple light paths, which arrive at
different times.
6. Which connector type uses a bayonet-style twist-lock mechanism?
A. SC
B. ST
C. LC
D. MTP/MPO
Rationale: ST connectors use a bayonet-type coupling.
7. What device measures optical power levels?
A. OTDR
B. Optical power meter
C. Fusion splicer
D. VFL
Rationale: The power meter directly measures the strength of optical
signals.
8. An OTDR is primarily used to:
A. Generate test light
B. Polish fiber ends
, C. Locate faults and measure splice losses
D. Certify copper cables
Rationale: OTDRs display reflections to detect faults, bends, and splice
locations.
9. The numerical aperture (NA) of a fiber determines its:
A. Bandwidth
B. Light-gathering ability
C. Shear strength
D. Connector type
Rationale: NA defines the acceptance angle for incoming light.
10. The standard wavelength for long-haul fiber optic communication is:
A. 650 nm
B. 850 nm
C. 980 nm
D. 1550 nm
Rationale: 1550 nm provides lowest attenuation in silica fibers.
11. What component keeps fiber ends precisely aligned during mating?
A. Strain relief
B. Ferrule
C. Jacket
D. Aramid yarn
Rationale: Ferrules hold fiber ends in alignment inside connectors.
12. Which fiber type supports the highest bandwidth?
A. Multimode step-index
B. Multimode graded-index
C. Single-mode fiber
D. Plastic fiber
Rationale: Single-mode eliminates modal dispersion, providing greatest
bandwidth.
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
A. Increase in optical signal strength
B. Loss of optical signal power over distance
C. Change in cable frequency
D. Heat generated by optical fibers
Rationale: Attenuation is the gradual reduction of signal power as light
travels through the fiber.
2. Which fiber type is commonly used for long-distance
telecommunications?
A. Multimode step-index
B. Multimode graded-index
C. Single-mode fiber
D. Plastic optical fiber
Rationale: Single-mode fiber allows long-distance transmission with
minimal dispersion.
3. The glass core of a single-mode fiber typically has a diameter of:
A. 100 µm
B. 62.5 µm
C. 8–10 µm
D. 125 µm
Rationale: Single-mode fiber cores are very small, around 8–10 microns.
,4. What is the purpose of cladding in an optical fiber?
A. Increase fiber strength
B. Provide electric insulation
C. Maintain total internal reflection
D. Produce light
Rationale: Cladding ensures the light stays confined in the core through
total internal reflection.
5. The primary cause of dispersion in multimode fiber is:
A. Chromatic dispersion
B. Modal dispersion
C. Thermal dispersion
D. Oscillation
Rationale: Multimode fibers carry multiple light paths, which arrive at
different times.
6. Which connector type uses a bayonet-style twist-lock mechanism?
A. SC
B. ST
C. LC
D. MTP/MPO
Rationale: ST connectors use a bayonet-type coupling.
7. What device measures optical power levels?
A. OTDR
B. Optical power meter
C. Fusion splicer
D. VFL
Rationale: The power meter directly measures the strength of optical
signals.
8. An OTDR is primarily used to:
A. Generate test light
B. Polish fiber ends
, C. Locate faults and measure splice losses
D. Certify copper cables
Rationale: OTDRs display reflections to detect faults, bends, and splice
locations.
9. The numerical aperture (NA) of a fiber determines its:
A. Bandwidth
B. Light-gathering ability
C. Shear strength
D. Connector type
Rationale: NA defines the acceptance angle for incoming light.
10. The standard wavelength for long-haul fiber optic communication is:
A. 650 nm
B. 850 nm
C. 980 nm
D. 1550 nm
Rationale: 1550 nm provides lowest attenuation in silica fibers.
11. What component keeps fiber ends precisely aligned during mating?
A. Strain relief
B. Ferrule
C. Jacket
D. Aramid yarn
Rationale: Ferrules hold fiber ends in alignment inside connectors.
12. Which fiber type supports the highest bandwidth?
A. Multimode step-index
B. Multimode graded-index
C. Single-mode fiber
D. Plastic fiber
Rationale: Single-mode eliminates modal dispersion, providing greatest
bandwidth.
