AR FO Fiber Optics Contractor Exam
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
1. What is the primary function of an optical fiber in a
communications system?
A. Convert optical signals into electrical signals
B. Carry electrical current over long distances
C. Transmit information using pulses of light
D. Amplify radio-frequency signals
Rationale: Optical fiber carries information by transmitting modulated
light through a glass or plastic core. Unlike copper conductors, it does
not rely on electrical current to transport the communication signal.
2. Which two materials are most commonly used to construct
optical-fiber cores?
A. Copper and aluminum
, B. Glass and plastic
C. Steel and brass
D. PVC and polyethylene
Rationale: Most telecommunications fiber uses high-purity glass, while
plastic optical fiber is used in certain short-distance applications. Glass
provides very low attenuation and supports long-distance, high-
bandwidth communication.
3. What principle allows light to remain confined within the core of
an optical fiber?
A. Electromagnetic induction
B. Diffraction
C. Polarization
D. Total internal reflection
Rationale: Total internal reflection occurs when light traveling through a
higher-index medium encounters a lower-index boundary at an angle
greater than the critical angle. This keeps the light primarily confined
within the fiber core.
4. What is the purpose of the cladding surrounding an optical-fiber
core?
A. Provide electrical grounding
B. Increase the fiber's weight
, C. Provide a lower refractive index that helps confine light in the
core
D. Carry electrical power to the receiver
Rationale: The cladding has a lower refractive index than the core. This
index difference is essential for maintaining the conditions needed for
total internal reflection and efficient light transmission.
5. Which type of fiber generally has a larger core diameter?
A. Single-mode fiber
B. Multimode fiber
C. Polarization-maintaining fiber
D. Dispersion-shifted fiber
Rationale: Multimode fiber typically has a much larger core than single-
mode fiber. The larger core permits multiple propagation modes and
makes multimode fiber useful for shorter-distance communications.
6. What is the typical core diameter of standard single-mode
telecommunications fiber?
A. 50 µm
B. 62.5 µm
C. Approximately 9 µm
D. 125 µm
, Rationale: Standard single-mode fiber has a core diameter of
approximately 8–10 micrometers, commonly specified as about 9 µm.
Its small core allows only one primary propagation mode at the
operating wavelength.
7. A common multimode fiber core diameter is:
A. 5 µm
B. 9 µm
C. 50 µm
D. 200 µm
Rationale: Modern multimode fiber commonly uses a 50-µm core. Older
multimode systems may use 62.5-µm fiber, but 50 µm is widely used in
current high-speed premises and data-center applications.
8. What does the term "fiber attenuation" describe?
A. Increase in optical power along the fiber
B. Increase in fiber diameter
C. Loss of optical signal power as light travels through the fiber
D. Conversion of light into radio waves
Rationale: Attenuation is the reduction in optical power as a signal
travels through a fiber. It is commonly expressed in decibels per
kilometer (dB/km).
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
1. What is the primary function of an optical fiber in a
communications system?
A. Convert optical signals into electrical signals
B. Carry electrical current over long distances
C. Transmit information using pulses of light
D. Amplify radio-frequency signals
Rationale: Optical fiber carries information by transmitting modulated
light through a glass or plastic core. Unlike copper conductors, it does
not rely on electrical current to transport the communication signal.
2. Which two materials are most commonly used to construct
optical-fiber cores?
A. Copper and aluminum
, B. Glass and plastic
C. Steel and brass
D. PVC and polyethylene
Rationale: Most telecommunications fiber uses high-purity glass, while
plastic optical fiber is used in certain short-distance applications. Glass
provides very low attenuation and supports long-distance, high-
bandwidth communication.
3. What principle allows light to remain confined within the core of
an optical fiber?
A. Electromagnetic induction
B. Diffraction
C. Polarization
D. Total internal reflection
Rationale: Total internal reflection occurs when light traveling through a
higher-index medium encounters a lower-index boundary at an angle
greater than the critical angle. This keeps the light primarily confined
within the fiber core.
4. What is the purpose of the cladding surrounding an optical-fiber
core?
A. Provide electrical grounding
B. Increase the fiber's weight
, C. Provide a lower refractive index that helps confine light in the
core
D. Carry electrical power to the receiver
Rationale: The cladding has a lower refractive index than the core. This
index difference is essential for maintaining the conditions needed for
total internal reflection and efficient light transmission.
5. Which type of fiber generally has a larger core diameter?
A. Single-mode fiber
B. Multimode fiber
C. Polarization-maintaining fiber
D. Dispersion-shifted fiber
Rationale: Multimode fiber typically has a much larger core than single-
mode fiber. The larger core permits multiple propagation modes and
makes multimode fiber useful for shorter-distance communications.
6. What is the typical core diameter of standard single-mode
telecommunications fiber?
A. 50 µm
B. 62.5 µm
C. Approximately 9 µm
D. 125 µm
, Rationale: Standard single-mode fiber has a core diameter of
approximately 8–10 micrometers, commonly specified as about 9 µm.
Its small core allows only one primary propagation mode at the
operating wavelength.
7. A common multimode fiber core diameter is:
A. 5 µm
B. 9 µm
C. 50 µm
D. 200 µm
Rationale: Modern multimode fiber commonly uses a 50-µm core. Older
multimode systems may use 62.5-µm fiber, but 50 µm is widely used in
current high-speed premises and data-center applications.
8. What does the term "fiber attenuation" describe?
A. Increase in optical power along the fiber
B. Increase in fiber diameter
C. Loss of optical signal power as light travels through the fiber
D. Conversion of light into radio waves
Rationale: Attenuation is the reduction in optical power as a signal
travels through a fiber. It is commonly expressed in decibels per
kilometer (dB/km).
