CA D-74 Fiber Optic Systems 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 electrical energy into mechanical energy
B. Transmit information using pulses of light
C. Increase electrical voltage
D. Store electrical signals
Answer: B. Transmit information using pulses of light
Rationale: Optical fiber carries information by transmitting modulated
light through a glass or plastic core. Because the signal is optical
rather than electrical, fiber provides high bandwidth and strong
immunity to electromagnetic interference.
,2. Which part of an optical fiber primarily carries the transmitted
light?
A. Cladding
B. Buffer coating
C. Core
D. Strength member
Answer: C. Core
Rationale: The core is the central portion of the fiber through which
the majority of the optical signal travels. The surrounding cladding
has a lower refractive index and helps keep the light confined within
the core.
3. What is the main purpose of the cladding surrounding a fiber core?
A. Provide electrical grounding
B. Protect the fiber from water only
C. Keep light confined within the core
D. Increase cable weight
Answer: C. Keep light confined within the core
Rationale: The cladding has a lower refractive index than the core,
allowing the fiber to guide light through internal reflection. It is an
,essential optical component, not merely a mechanical protective
layer.
4. Which type of fiber generally has the smallest core diameter?
A. Multimode fiber
B. Single-mode fiber
C. Plastic optical fiber
D. Ribbon fiber
Answer: B. Single-mode fiber
Rationale: Standard single-mode fiber has a very small core,
commonly around 8–10 micrometers in diameter. Its small core allows
essentially one propagation mode and makes it suitable for long-
distance, high-bandwidth transmission.
5. Which fiber type is commonly used for shorter-distance premises
networks?
A. Single-mode only
B. Multimode
C. Coaxial-only fiber
D. Copper-clad fiber
Answer: B. Multimode
, Rationale: Multimode fiber has a larger core and can support multiple
light propagation modes. It is commonly used for shorter-distance
applications such as building backbone networks and data-center
connections.
6. What does attenuation describe in an optical fiber system?
A. Increase in optical power
B. Loss of optical signal power
C. Increase in fiber diameter
D. Electrical grounding resistance
Answer: B. Loss of optical signal power
Rationale: Attenuation is the reduction in optical power as light
travels through a fiber or encounters components such as connectors
and splices. It is normally expressed in decibels, often as dB/km for
fiber.
7. Which unit is commonly used to express fiber attenuation per unit
length?
A. Volts per meter
B. Amperes per kilometer
C. Decibels per kilometer
D. Ohms per kilometer
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 electrical energy into mechanical energy
B. Transmit information using pulses of light
C. Increase electrical voltage
D. Store electrical signals
Answer: B. Transmit information using pulses of light
Rationale: Optical fiber carries information by transmitting modulated
light through a glass or plastic core. Because the signal is optical
rather than electrical, fiber provides high bandwidth and strong
immunity to electromagnetic interference.
,2. Which part of an optical fiber primarily carries the transmitted
light?
A. Cladding
B. Buffer coating
C. Core
D. Strength member
Answer: C. Core
Rationale: The core is the central portion of the fiber through which
the majority of the optical signal travels. The surrounding cladding
has a lower refractive index and helps keep the light confined within
the core.
3. What is the main purpose of the cladding surrounding a fiber core?
A. Provide electrical grounding
B. Protect the fiber from water only
C. Keep light confined within the core
D. Increase cable weight
Answer: C. Keep light confined within the core
Rationale: The cladding has a lower refractive index than the core,
allowing the fiber to guide light through internal reflection. It is an
,essential optical component, not merely a mechanical protective
layer.
4. Which type of fiber generally has the smallest core diameter?
A. Multimode fiber
B. Single-mode fiber
C. Plastic optical fiber
D. Ribbon fiber
Answer: B. Single-mode fiber
Rationale: Standard single-mode fiber has a very small core,
commonly around 8–10 micrometers in diameter. Its small core allows
essentially one propagation mode and makes it suitable for long-
distance, high-bandwidth transmission.
5. Which fiber type is commonly used for shorter-distance premises
networks?
A. Single-mode only
B. Multimode
C. Coaxial-only fiber
D. Copper-clad fiber
Answer: B. Multimode
, Rationale: Multimode fiber has a larger core and can support multiple
light propagation modes. It is commonly used for shorter-distance
applications such as building backbone networks and data-center
connections.
6. What does attenuation describe in an optical fiber system?
A. Increase in optical power
B. Loss of optical signal power
C. Increase in fiber diameter
D. Electrical grounding resistance
Answer: B. Loss of optical signal power
Rationale: Attenuation is the reduction in optical power as light
travels through a fiber or encounters components such as connectors
and splices. It is normally expressed in decibels, often as dB/km for
fiber.
7. Which unit is commonly used to express fiber attenuation per unit
length?
A. Volts per meter
B. Amperes per kilometer
C. Decibels per kilometer
D. Ohms per kilometer
