Contractor Exam Questions And

CA D74 Fiber Optic Systems Contractor Exam Questions And Correct Answers (Verified Answers) Plus Rationale2026 Q&A| Instant Download Pdf

• What is the primary advantage of fiber optic cables over copper cables?
• Lower cost
• Easier installation
• Higher bandwidth and longer distance transmission
• Greater flexibility

Higher bandwidth and longer distance transmission are the main advantages because fiber optics can carry more data with less signal loss over long distances.

• What type of fiber is most commonly used for long-distance

telecommunication?

• Multimode
• Plastic optical fiber
• Single-mode
• Step-index fiber

Single-mode fiber allows signals to travel longer distances with minimal attenuation, making it ideal for telecommunications.

• What is the typical core diameter of single-mode fiber?
• 50 µm
• 62.5 µm
• 8–10 µm
• 100 µm 1 / 3

Single-mode fibers have a small core to allow only one light mode to propagate, reducing modal dispersion.

• Which light source is commonly used in multimode fiber systems?
• Laser diode

B. LED

• Solar light
• Halogen lamp

LEDs are cheaper and easier to couple with multimode fiber for short-distance applications.

5. The attenuation of fiber optic cables is usually measured in:

• Ohms
• Watts
• Decibels per kilometer (dB/km)
• Volts

Attenuation measures signal loss over distance and is expressed in dB/km.

• Which connector type is widely used in fiber optic networks?

A. RJ-45

B. BNC

• SC

D. USB

SC connectors are standardized, easy to install, and commonly used in fiber networks.

• What is the main cause of chromatic dispersion in fiber optic cables?
• Bending of the fiber
• Different wavelengths traveling at different speeds
• Connector loss
• Splice loss

Chromatic dispersion occurs because different wavelengths of light propagate at different speeds, causing pulse broadening.

8. A fiber optic splice is used to:

• Terminate a cable
• Join two fibers together
• Amplify the signal
• Convert optical signal to electrical

Splicing connects fibers permanently to minimize signal loss and reflection. 2 / 3

• What is the typical loss of a fusion splice?
• 0.1–0.3 dB
• 1–2 dB
• 0.05–0.1 dB
• 2–3 dB

Fusion splicing aligns and fuses fibers, creating very low-loss connections.

• Which safety precaution is critical when handling fiber optic

cables?

• Wearing gloves
• Avoiding eye exposure to laser light
• Using pliers
• Applying heat to the fiber

Laser light can cause permanent eye damage; proper eye safety is essential.

• What type of fiber has a larger core diameter?
• Single-mode
• Multimode
• Polarization-maintaining
• Dispersion-shifted

Multimode fibers have larger cores (50–62.5 µm) to support multiple light modes.

• What is PMD in fiber optics?
• Pulse-mode dispersion
• Power-mode difference
• Polarization mode dispersion
• Phase modulation distortion

PMD is caused by differential propagation speeds of polarized light modes, affecting high-speed transmission.

• Which tool is used to measure optical power in fiber?
• Multimeter
• Oscilloscope
• Optical power meter
• Signal generator

Optical power meters directly measure the light power in fiber systems.

• / 3