CO Fiber Optics Contractor Exam Questions
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
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1. What is the primary function of an optical fiber in a
communications system?
A. To generate electrical power
B. To convert AC voltage to DC voltage
C. To transmit information using pulses of light
D. To increase electrical resistance
Rationale: Optical fiber carries information by transmitting modulated
light through a glass or plastic core. Because light experiences very
low attenuation in properly designed fiber, it can carry large amounts
of data over long distances.
2. Which part of an optical fiber primarily carries the light signal?
A. Jacket
, B. Core
C. Strength member
D. Buffer tube
Rationale: The core is the central region of the fiber through which the
optical signal travels. It is surrounded by cladding, which has a lower
refractive index and helps confine light within the core.
3. What is the main purpose of the cladding surrounding an optical
fiber core?
A. To provide electrical grounding
B. To increase cable weight
C. To confine light within the core
D. To provide mechanical pulling strength
Rationale: Cladding has a lower refractive index than the core,
allowing light to remain confined through total internal reflection. It
also provides a protective interface between the core and outer
protective layers.
4. Which phenomenon allows light to remain confined within an
optical fiber?
A. Electromagnetic induction
B. Diffraction
, C. Total internal reflection
D. Electrical conduction
Rationale: Total internal reflection occurs when light traveling
through a higher-refractive-index medium strikes a lower-refractive-
index boundary at an appropriate angle. This principle allows optical
signals to travel along the fiber.
5. Which fiber type generally has the smallest core diameter?
A. Multimode step-index
B. Multimode graded-index
C. Single-mode
D. Plastic optical fiber
Rationale: Single-mode fiber typically has a core of approximately 8–
10 micrometers. Its small core permits essentially one propagation
mode, making it suitable for high-bandwidth and long-distance
applications.
6. Which fiber type is commonly used for long-distance
telecommunications?
A. Multimode fiber
B. Single-mode fiber
C. Plastic fiber only
D. Coaxial fiber
, Rationale: Single-mode fiber has low attenuation and low modal
dispersion, allowing signals to travel much farther than typical
multimode systems. It is widely used for telecommunications,
backbone networks, and long-haul links.
7. What is a major characteristic of multimode fiber?
A. It has no cladding
B. It supports multiple propagation modes
C. It uses electrical pulses instead of light
D. It cannot transmit digital information
Rationale: Multimode fiber has a larger core that allows multiple
paths, or modes, for light to propagate. Modal dispersion can limit its
distance compared with single-mode fiber.
8. Which measurement is commonly used to express optical power?
A. Ohms
B. Amperes
C. dBm
D. Hertz
Rationale: Optical power is commonly expressed in dBm, which is a
logarithmic unit referenced to 1 milliwatt. Optical meters use dBm to
indicate received or transmitted power levels.
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. To generate electrical power
B. To convert AC voltage to DC voltage
C. To transmit information using pulses of light
D. To increase electrical resistance
Rationale: Optical fiber carries information by transmitting modulated
light through a glass or plastic core. Because light experiences very
low attenuation in properly designed fiber, it can carry large amounts
of data over long distances.
2. Which part of an optical fiber primarily carries the light signal?
A. Jacket
, B. Core
C. Strength member
D. Buffer tube
Rationale: The core is the central region of the fiber through which the
optical signal travels. It is surrounded by cladding, which has a lower
refractive index and helps confine light within the core.
3. What is the main purpose of the cladding surrounding an optical
fiber core?
A. To provide electrical grounding
B. To increase cable weight
C. To confine light within the core
D. To provide mechanical pulling strength
Rationale: Cladding has a lower refractive index than the core,
allowing light to remain confined through total internal reflection. It
also provides a protective interface between the core and outer
protective layers.
4. Which phenomenon allows light to remain confined within an
optical fiber?
A. Electromagnetic induction
B. Diffraction
, C. Total internal reflection
D. Electrical conduction
Rationale: Total internal reflection occurs when light traveling
through a higher-refractive-index medium strikes a lower-refractive-
index boundary at an appropriate angle. This principle allows optical
signals to travel along the fiber.
5. Which fiber type generally has the smallest core diameter?
A. Multimode step-index
B. Multimode graded-index
C. Single-mode
D. Plastic optical fiber
Rationale: Single-mode fiber typically has a core of approximately 8–
10 micrometers. Its small core permits essentially one propagation
mode, making it suitable for high-bandwidth and long-distance
applications.
6. Which fiber type is commonly used for long-distance
telecommunications?
A. Multimode fiber
B. Single-mode fiber
C. Plastic fiber only
D. Coaxial fiber
, Rationale: Single-mode fiber has low attenuation and low modal
dispersion, allowing signals to travel much farther than typical
multimode systems. It is widely used for telecommunications,
backbone networks, and long-haul links.
7. What is a major characteristic of multimode fiber?
A. It has no cladding
B. It supports multiple propagation modes
C. It uses electrical pulses instead of light
D. It cannot transmit digital information
Rationale: Multimode fiber has a larger core that allows multiple
paths, or modes, for light to propagate. Modal dispersion can limit its
distance compared with single-mode fiber.
8. Which measurement is commonly used to express optical power?
A. Ohms
B. Amperes
C. dBm
D. Hertz
Rationale: Optical power is commonly expressed in dBm, which is a
logarithmic unit referenced to 1 milliwatt. Optical meters use dBm to
indicate received or transmitted power levels.
