Exam Practice Test Questions And

Fiber Optic Technician Certification Exam Practice Test Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What does “dB” stand for in fiber optics?
• Decibel
• Decibel ratio
• Data bandwidth
• Digital base

Rationale: dB stands for decibel, a logarithmic unit used to express

the ratio of power levels, often used in fiber optics to measure signal loss or gain.

• What is the typical wavelength used in single-mode fiber

transmission?

• 650 nm 1 / 4

• 850 nm
• 1310 nm
• 700 nm

Rationale: 1310 nm and 1550 nm are standard wavelengths for

single-mode fiber, offering low attenuation and dispersion.

• Which type of fiber has a larger core diameter?
• Multimode fiber
• Single-mode fiber
• Polarized fiber
• Gradient fiber

Rationale: Multimode fiber has a larger core (50 or 62.5 µm) allowing

multiple light paths, unlike single-mode fibers with 8–10 µm cores.

• What is the purpose of a fiber optic connector?
• To amplify the signal
• To clean the fiber
• To join two fibers with minimal loss
• To convert light to electricity

Rationale: Connectors align and join fibers, enabling signal continuity

with minimal optical loss.

• Which component converts electrical signals into optical signals?
• Transmitter
• Receiver
• Repeater 2 / 4

• Amplifier

Rationale: The transmitter, often using an LED or laser diode,

converts electrical signals into light signals.

• Which tool measures optical power in a fiber?
• Optical power meter

B. OTDR

• Light source
• Fusion splicer

Rationale: An optical power meter measures light power at the

fiber’s output, indicating signal strength or loss.

• What is the main cause of attenuation in optical fiber?
• Electromagnetic interference
• Absorption and scattering
• Reflection losses
• Refraction

Rationale: Attenuation results primarily from absorption of light

energy and scattering due to imperfections in the fiber.

• What is the function of a fusion splicer?
• To cut cables
• To test cable length
• To permanently join two fibers by fusing them together
• To polish connectors 3 / 4

Rationale: A fusion splicer precisely aligns and melts fiber ends to

form a low-loss permanent connection.

• Which type of light source is typically used for single-mode fibers?

A. LED

• Laser diode
• Incandescent bulb
• Halogen lamp

Rationale: Laser diodes provide coherent, narrow beams ideal for

single-mode transmission.

• Which device measures backscattered light to locate faults?
• Power meter
• OTDR (Optical Time Domain Reflectometer)
• Light source
• Connector microscope

Rationale: An OTDR measures backscattered light to analyze fiber

length, losses, and fault locations.

• What is the typical core diameter of single-mode fiber?
• 62.5 µm
• 50 µm
• 8–10 µm
• 100 µm

Rationale: Single-mode fiber has a small core (8–10 µm) to allow only

one light mode for minimal dispersion.

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