Fiber Optic Technician Certification
(CFOT) Practice Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. Which type of fiber optic cable has a core diameter of 50 µm or 62.5
µm?
A. Single-mode
B. Multimode
C. Plastic Optical Fiber
D. Step-index single-mode
Rationale: Multimode fiber has larger core diameters (50 µm or 62.5
µm) to allow multiple light modes to propagate.
2. What is the typical core diameter of single-mode fiber?
A. 50 µm
, B. 62.5 µm
C. 8–10 µm
D. 100 µm
Rationale: Single-mode fiber has a very small core (8–10 µm) to allow
only one mode of light to propagate, reducing modal dispersion.
3. What is the primary advantage of single-mode fiber over multimode
fiber?
A. Lower cost
B. Easier installation
C. Longer transmission distance
D. More light modes
Rationale: Single-mode fiber can transmit signals over longer
distances without significant signal loss or modal dispersion.
4. Which type of light source is commonly used for single-mode fiber?
A. LED
B. Laser diode
C. Incandescent bulb
D. Fluorescent lamp
Rationale: Laser diodes produce coherent, narrow beams suitable for
single-mode fiber transmission.
5. In fiber optics, what does attenuation refer to?
A. Signal reflection
B. Core diameter
, C. Loss of signal power over distance
D. Connector type
Rationale: Attenuation is the reduction in signal strength as light
travels through the fiber.
6. What is the typical attenuation for single-mode fiber at 1550 nm?
A. 0.5 dB/km
B. 2.0 dB/km
C. 0.2 dB/km
D. 1.0 dB/km
Rationale: Single-mode fiber exhibits very low attenuation at 1550
nm, typically around 0.2 dB/km.
7. Which connector type is widely used in telecommunications?
A. ST
B. FC
C. SC
D. MTRJ
Rationale: SC connectors are popular in telecom because they are
easy to install and reliable for repeated connections.
8. What is the main function of a fiber optic patch panel?
A. Increase bandwidth
B. Reduce attenuation
C. Organize and manage fiber connections
D. Amplify the signal
, Rationale: Patch panels provide a central point to terminate,
manage, and organize fiber optic cables.
9. Which type of fiber optic cable has a solid plastic core and is usually
used for short-distance applications?
A. Single-mode
B. Multimode
C. Plastic Optical Fiber (POF)
D. Graded-index fiber
Rationale: Plastic Optical Fiber has a large plastic core, is flexible,
and is suitable for short-range applications.
10. What causes modal dispersion in multimode fiber?
A. Connector loss
B. Different light modes traveling at different speeds
C. Fiber attenuation
D. Fiber bends
Rationale: Modal dispersion occurs because multiple light modes
arrive at the end of the fiber at different times, causing signal
broadening.
11. Which tool is used to measure optical power in fiber?
A. OTDR
B. Visual fault locator
C. Optical power meter
D. Fusion splicer
(CFOT) Practice Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. Which type of fiber optic cable has a core diameter of 50 µm or 62.5
µm?
A. Single-mode
B. Multimode
C. Plastic Optical Fiber
D. Step-index single-mode
Rationale: Multimode fiber has larger core diameters (50 µm or 62.5
µm) to allow multiple light modes to propagate.
2. What is the typical core diameter of single-mode fiber?
A. 50 µm
, B. 62.5 µm
C. 8–10 µm
D. 100 µm
Rationale: Single-mode fiber has a very small core (8–10 µm) to allow
only one mode of light to propagate, reducing modal dispersion.
3. What is the primary advantage of single-mode fiber over multimode
fiber?
A. Lower cost
B. Easier installation
C. Longer transmission distance
D. More light modes
Rationale: Single-mode fiber can transmit signals over longer
distances without significant signal loss or modal dispersion.
4. Which type of light source is commonly used for single-mode fiber?
A. LED
B. Laser diode
C. Incandescent bulb
D. Fluorescent lamp
Rationale: Laser diodes produce coherent, narrow beams suitable for
single-mode fiber transmission.
5. In fiber optics, what does attenuation refer to?
A. Signal reflection
B. Core diameter
, C. Loss of signal power over distance
D. Connector type
Rationale: Attenuation is the reduction in signal strength as light
travels through the fiber.
6. What is the typical attenuation for single-mode fiber at 1550 nm?
A. 0.5 dB/km
B. 2.0 dB/km
C. 0.2 dB/km
D. 1.0 dB/km
Rationale: Single-mode fiber exhibits very low attenuation at 1550
nm, typically around 0.2 dB/km.
7. Which connector type is widely used in telecommunications?
A. ST
B. FC
C. SC
D. MTRJ
Rationale: SC connectors are popular in telecom because they are
easy to install and reliable for repeated connections.
8. What is the main function of a fiber optic patch panel?
A. Increase bandwidth
B. Reduce attenuation
C. Organize and manage fiber connections
D. Amplify the signal
, Rationale: Patch panels provide a central point to terminate,
manage, and organize fiber optic cables.
9. Which type of fiber optic cable has a solid plastic core and is usually
used for short-distance applications?
A. Single-mode
B. Multimode
C. Plastic Optical Fiber (POF)
D. Graded-index fiber
Rationale: Plastic Optical Fiber has a large plastic core, is flexible,
and is suitable for short-range applications.
10. What causes modal dispersion in multimode fiber?
A. Connector loss
B. Different light modes traveling at different speeds
C. Fiber attenuation
D. Fiber bends
Rationale: Modal dispersion occurs because multiple light modes
arrive at the end of the fiber at different times, causing signal
broadening.
11. Which tool is used to measure optical power in fiber?
A. OTDR
B. Visual fault locator
C. Optical power meter
D. Fusion splicer
