10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The FOT exam has 75 questions and runs 2 hours.
These 10 free FOT questions are organized by exam domain, so you can see how each part of the Fiber Optics Technician (FOT) blueprint is tested. Reveal the answer and explanation under each question.
At the specified test wavelength, a source delivers -3 dBm at the input of a passive fiber link, and the power measured at the far end is -12 dBm. Which value belongs in the report field labeled "Link insertion loss"?
Correct answer: B - 9 dB
Closing a splice-tray cover introduces a new loss event on a single-mode link. At the tray location, the OTDR measures 0.08 dB of loss at 1310 nm and 1.70 dB at 1550 nm. The event is nonreflective, and backscatter continues beyond it. Which fault best fits this combination?
Correct answer: A - Macrobending of stored fiber
During fault isolation, a coworker raises a direct-view inspection microscope to a disconnected single-mode connector. The far-end transmitter status is unknown. The coworker says, "There is no visible glow, so it is safe to inspect." What should happen before the connector is viewed?
Correct answer: A - Isolate all sources and verify no optical power with a suitable meter.
A rack installation requires the fibers of one incoming cable to separate into individually jacketed, strength-member-reinforced subunits for direct termination at different equipment ports. No field-installed furcation kit is to be used. Which cable construction provides those subunits?
Correct answer: C - Breakout cable
Repeatable OTDR measurements of one fusion splice show -0.10 dB in one direction and +0.34 dB in the reverse direction, using the same wavelength. The contract accepts splice loss of 0.20 dB or less based on the bidirectional average. What is the correct disposition of this splice?
Correct answer: C - Accept it; the bidirectional splice loss is 0.12 dB.
After cleaning, an LC patch-cord endface passes video inspection. It picks up particles every time it is mated to one panel port. A second cord, verified clean immediately before mating, shows the same transfer. Which action targets the recurring contamination source?
Correct answer: A - Inspect and clean the panel-side mating connector.
A short single-mode link has persistent receive errors. The optics have compatible wavelengths, and the connector endfaces are clean. A calibrated meter measures -5 dBm at the receiver. Its datasheet specifies an operating input range of -20 to -8 dBm and an absolute maximum input of 0 dBm. Which adjustment directly addresses the out-of-range condition?
Correct answer: D - Add suitable attenuation to bring the input within the operating range.
Sixteen homes share one OLT port through a single-stage 1:16 passive splitter. Fifteen ONTs remain registered with normal received power. At the remaining home, the ONT is powered but reports loss of downstream optical signal immediately after work on its drop cable. The most efficient place to begin optical fault isolation is:
Correct answer: D - The subscriber's splitter output and drop
A proposed single-mode link uses a transmitter rated at -5 dBm minimum and -2 dBm typical output, with receiver sensitivity of -18 dBm. The design allows 10 km of fiber at 0.4 dB/km, four mated connector pairs at 0.5 dB per pair, and ten splices at 0.1 dB each. A proposed passive module adds 4.0 dB. The customer requires at least 3.0 dB of reserve above receiver sensitivity. Does the proposal satisfy the worst-case low-power budget?
Correct answer: D - No; only 2.0 dB of reserve remains.
Two documented connectors, 4 m apart near the middle of a 500 m link, appear as one merged event on an OTDR trace. Launch and receive fibers are installed, and the trace has ample signal above the noise floor. Which change is most likely to resolve the two events?
Correct answer: B - Shorten the optical pulse width.
The FOT exam also covers these domains. Drill them in the full free practice test:
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