Fiber Optic Technician Certification
(CFOT) Practice Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A Instant Download
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1. What is the core function of an optical fiber?
A. Conduct electricity
B. Transmit light signals
C. Store data
D. Amplify signals
Answer: Transmit light signals
Rationale: Optical fibers are designed to guide light signals for
communication purposes.
2. What material is most commonly used for fiber optic cores?
A. Copper
B. Plastic
C. Glass
D. Aluminum
Answer: Glass
Rationale: High-purity silica glass is commonly used due to its excellent
light transmission properties.
,3. What does attenuation refer to in fiber optics?
A. Signal amplification
B. Signal loss over distance
C. Signal reflection
D. Signal conversion
Answer: Signal loss over distance
Rationale: Attenuation measures how much signal strength is lost as light
travels through fiber.
4. Which type of fiber has a larger core diameter?
A. Single-mode
B. Multimode
C. Plastic
D. Coaxial
Answer: Multimode
Rationale: Multimode fiber has a larger core (50 or 62.5 microns)
compared to single-mode fiber (~9 microns).
5. What is the typical core size of single-mode fiber?
A. 50 microns
B. 62.5 microns
C. 9 microns
D. 100 microns
Answer: 9 microns
Rationale: Single-mode fiber uses a small core to allow only one
propagation mode.
6. What does numerical aperture (NA) describe?
A. Fiber length
B. Light-gathering ability
C. Signal speed
D. Connector type
Answer: Light-gathering ability
Rationale: NA defines the acceptance angle of light entering the fiber.
, 7. What is modal dispersion?
A. Signal loss
B. Signal distortion due to multiple paths
C. Electrical interference
D. Connector damage
Answer: Signal distortion due to multiple paths
Rationale: In multimode fiber, different modes travel at different speeds,
causing dispersion.
8. Which light source is used in single-mode fiber?
A. LED
B. Laser diode
C. Halogen lamp
D. Fluorescent lamp
Answer: Laser diode
Rationale: Laser diodes provide coherent light suitable for long-distance
single-mode transmission.
9. What wavelength is commonly used in fiber optics?
A. 450 nm
B. 850 nm
C. 1200 nm
D. 2000 nm
Answer: 850 nm
Rationale: 850 nm is a standard wavelength used in multimode fiber
systems.
10.What is total internal reflection?
A. Light escaping fiber
B. Light bouncing within the core
C. Light absorption
D. Light scattering
Answer: Light bouncing within the core
(CFOT) Practice Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A Instant Download
1. What is the core function of an optical fiber?
A. Conduct electricity
B. Transmit light signals
C. Store data
D. Amplify signals
Answer: Transmit light signals
Rationale: Optical fibers are designed to guide light signals for
communication purposes.
2. What material is most commonly used for fiber optic cores?
A. Copper
B. Plastic
C. Glass
D. Aluminum
Answer: Glass
Rationale: High-purity silica glass is commonly used due to its excellent
light transmission properties.
,3. What does attenuation refer to in fiber optics?
A. Signal amplification
B. Signal loss over distance
C. Signal reflection
D. Signal conversion
Answer: Signal loss over distance
Rationale: Attenuation measures how much signal strength is lost as light
travels through fiber.
4. Which type of fiber has a larger core diameter?
A. Single-mode
B. Multimode
C. Plastic
D. Coaxial
Answer: Multimode
Rationale: Multimode fiber has a larger core (50 or 62.5 microns)
compared to single-mode fiber (~9 microns).
5. What is the typical core size of single-mode fiber?
A. 50 microns
B. 62.5 microns
C. 9 microns
D. 100 microns
Answer: 9 microns
Rationale: Single-mode fiber uses a small core to allow only one
propagation mode.
6. What does numerical aperture (NA) describe?
A. Fiber length
B. Light-gathering ability
C. Signal speed
D. Connector type
Answer: Light-gathering ability
Rationale: NA defines the acceptance angle of light entering the fiber.
, 7. What is modal dispersion?
A. Signal loss
B. Signal distortion due to multiple paths
C. Electrical interference
D. Connector damage
Answer: Signal distortion due to multiple paths
Rationale: In multimode fiber, different modes travel at different speeds,
causing dispersion.
8. Which light source is used in single-mode fiber?
A. LED
B. Laser diode
C. Halogen lamp
D. Fluorescent lamp
Answer: Laser diode
Rationale: Laser diodes provide coherent light suitable for long-distance
single-mode transmission.
9. What wavelength is commonly used in fiber optics?
A. 450 nm
B. 850 nm
C. 1200 nm
D. 2000 nm
Answer: 850 nm
Rationale: 850 nm is a standard wavelength used in multimode fiber
systems.
10.What is total internal reflection?
A. Light escaping fiber
B. Light bouncing within the core
C. Light absorption
D. Light scattering
Answer: Light bouncing within the core
