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ETA · Last updated November 2026

ETA Fiber Optics Technician (FOT): free practice test

FOT is ETA International's technician-level fiber certification and requires a current FOI. The written exam has 75 questions in 2 hours with a 75% pass mark and follows ETA's 16-area FOT competency list: transmission and light, fiber characteristics, splicing and connectors, sources, detectors, WDM and PON, worst-case power budgets, and OTDR and loss testing to TIA-568 and TIA-526. A hands-on course is also required; this prep covers only the written exam.

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About the ETA FOT exam

FOT is ETA International's technician-level fiber certification and requires a current FOI. The written exam has 75 questions in 2 hours with a 75% pass mark and follows ETA's 16-area FOT competency list: transmission and light, fiber characteristics, splicing and connectors, sources, detectors, WDM and PON, worst-case power budgets, and OTDR and loss testing to TIA-568 and TIA-526. A hands-on course is also required; this prep covers only the written exam.

What's on the exam

ETA FOT
Transmission Principles, Light and Decibels
8 key facts
Fiber Construction, Characteristics and Dispersion
8 key facts
Safety, Cables and Installation
8 key facts
Splicing and Connectors
8 key facts
Sources, Detectors, Passive Components and WDM
8 key facts
Passive Optical Networks
7 key facts
Link Power Budgets and System Design
7 key facts
OTDR, Loss Testing and Troubleshooting
8 key facts

Each branch is a topic in the official outline. Members see every key fact on the full mind map. Read the free study guide →

How to pass the ETA FOT exam

  • FOT goes beyond FOI into calculation and diagnosis: worst-case power budgets, dispersion, photodiode current and reading OTDR traces. Practise each type with a non-programmable calculator.
  • You need 75%, so about 57 of 75 in 2 hours. Budget questions take the longest; do quick recall items first and come back.
  • ETA's FOT list cites TIA-568-C.3 and TIA-526-14-B by edition, while newer editions exist. The core values have not changed: 0.75 dB per connector pair, 0.3 dB per splice, 3.5 and 1.5 dB/km multimode, 0.5 dB/km outside plant singlemode.
  • For any OTDR question, ask three things: is the event reflective, which direction was it shot from, and is it inside the dead zone.

Save your results and get your Readiness Score

Create a free account after the test: your score by topic, a mistakes bank, the complete study notes for the first topic, flashcards and the RCDD Numbers & Formulas Sheet.

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What's in the premium ETA FOT prep

Premium ETA FOT prep is studied one topic at a time. Each step starts with that topic's key notes and flashcard deck, then its own question sets of 25, so you master one topic before you move to the next. When every topic is strong, the 6 full mock exams show you're ready.

3,000practice questions, every answer explained
6full-length mock exams, 75 questions each, timed
800flashcards with spaced repetition, sorted by topic
60comprehensive key notes across 8 topics

Your step-by-step study path

  1. 1
    Transmission Principles, Light and Decibels8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Notes free with an account
  2. 2
    Fiber Construction, Characteristics and Dispersion8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  3. 3
    Safety, Cables and Installation8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  4. 4
    Splicing and Connectors8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  5. 5
    Sources, Detectors, Passive Components and WDM7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  6. 6
    Passive Optical Networks7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  7. 7
    Link Power Budgets and System Design7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  8. 8
    OTDR, Loss Testing and Troubleshooting7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  9. Final step: 6 full mock exams75 questions each, timed like test day. Pass them, then book your exam.
    Premium
Free with an account

Read the complete ETA FOT study notes for “Transmission Principles, Light and Decibels”

Our first full set of comprehensive notes, about 15 minutes of reading: From signal to light and back · Decibels for power and voltage · Wavelength and frequency · Refraction and reflection, a worked exam example, the traps examiners use and a one-minute recap. Create a free account to read it and see how premium notes work before you decide.

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Study tools included

3,000 practice questions

3,000 exam-style questions per exam, organized topic by topic in sets of 25. Every answer explained, with the rule it comes from.

6 full mock exams

6 full-length timed mock exams per exam, with real question counts and time limits, so test day feels like practice day.

Exam Readiness Score

One 0 to 100 number that tells you when you're ready to book. Reach 80 and you're covered by our Pass Guarantee.

800 flashcards + spaced repetition

800 flashcards per exam, in a deck for each topic, that come back right before you'd forget them. Five minutes a day keeps every number fresh.

60 comprehensive key notes

60 key notes per exam, split across its topics and each explained in full: the concepts, worked exam examples, the traps examiners use and a quick recap. Your first set is free with an account.

Mind maps

See the whole exam on one screen: every topic and the facts under it.

Sample questions with answers

These are the questions in the free test above, with answers. Try the test first. You'll learn more by getting some wrong.

1. A DWDM channel sits at 1550 nm. What is its optical frequency, using 3 x 10^8 m/s for the speed of light?
Answer: 193 THz. Frequency equals the speed of light divided by wavelength: 3 x 10^8 / 1550 x 10^-9 = 1.935 x 10^14 Hz, about 193 THz. DWDM grids are defined in frequency for this reason. 229 THz is the 1310 nm figure, and the other two slip a power of ten.
2. A receiver's preamplifier raises a signal from 10 mV to 100 mV across equal impedances. What is the gain in decibels?
Answer: 20 dB. Voltage ratios use 20 log: 20 x log (100 / 10) = 20 x 1 = 20 dB. A tenfold voltage increase is a hundredfold power increase, which is also 20 dB. Using 10 log on a voltage ratio gives 10 dB, a common slip.
3. A G.652 fiber has 17 ps/(nm·km) of chromatic dispersion at 1550 nm. A laser with 0.1 nm spectral width drives an 80 km span. How much pulse spreading results?
Answer: 136 ps. Chromatic dispersion spreading = dispersion coefficient x spectral width x length: 17 x 0.1 x 80 = 136 ps. Narrow-line DFB lasers keep the spectral width term small. Standard G.652 fiber has near-zero dispersion around 1310 nm but about 17 ps/(nm·km) at 1550 nm.
4. An older singlemode route runs 10 Gb/s without trouble. A 100 Gb/s upgrade over the same 120 km fails, though loss and chromatic dispersion are within limits. Which fiber property should be measured next?
Answer: Polarization mode dispersion. PMD comes from the two polarization states traveling at slightly different speeds (differential group delay). It is random, builds with length and hurts most at high bit rates, so older fiber that was fine at 10 Gb/s can fail at 100 Gb/s. Modal bandwidth applies only to multimode fiber.
5. A training shop installs a local exhaust hood over its epoxy curing ovens and splicing bench. In the three lines of defense for fiber safety, what is this?
Answer: An engineering control. The three lines of defense are engineering controls, personal protective equipment and good work habits. An exhaust hood changes the workplace itself to remove the hazard, so it is an engineering control, the first line. Safety glasses would be PPE, and keeping food away from the bench is a work habit.
6. An OTDR shows a reflective spike with 0.2 dB of loss at a joint that the records list as a splice. What type of splice is it most likely to be?
Answer: A mechanical splice. A mechanical splice leaves a tiny gap filled with index-matching gel, which still reflects a little light and shows as a reflective event. Fusion splices weld the glass and normally appear as non-reflective drops. A connector pair would be listed as a connection, not a splice.
7. An interferometer check of a singlemode UPC jumper shows an apex offset of 85 µm. What is the likely effect?
Answer: Poor fiber contact, raising loss and reflectance. Apex offset is the distance between the top of the polished dome and the fiber core. If it is too large (Telcordia GR-326 sets a limit of 50 µm), mating ferrules touch off the core, leaving a gap at the fibers that raises insertion loss and back-reflection. Repolish or replace the jumper.
8. A PIN photodiode has a responsivity of 0.85 A/W at 1310 nm and receives 20 µW. What photocurrent does it produce?
Answer: 17 µA. Photocurrent = responsivity x optical power = 0.85 A/W x 20 µW = 17 µA. Dividing power by responsivity gives 23.5, a units slip. Responsivity depends on wavelength and quantum efficiency, which is why data sheets quote it at specific wavelengths.
9. A carrier needs 40 wavelength channels over one fiber pair on an 80 km route, with optical amplification. Which approach fits?
Answer: DWDM on the ITU grid in the C-band. DWDM packs many channels closely (for example 100 GHz, about 0.8 nm, spacing) in the C-band, where erbium-doped fiber amplifiers boost all of them at once. CWDM uses 20 nm spacing across about 1270 to 1610 nm, so it offers at most 18 channels and cannot be amplified by one EDFA.
10. In a GPON FTTH network, an ONT receives downstream data but the OLT never hears it. On which wavelength should the ONT be transmitting?
Answer: 1310 nm. GPON (ITU-T G.984) sends downstream data at 1490 nm and upstream at 1310 nm, with 1550 nm available for RF video overlay. 1625 nm is used for out-of-service and live-fiber OTDR monitoring. Check the ONT's upstream optics and the drop for loss at 1310 nm.
11. A singlemode link has a minimum launch power of -3 dBm and a receiver sensitivity of -20 dBm. It has 18 km of outside plant fiber at 0.5 dB/km, 2 mated connector pairs at 0.75 dB and 6 splices at 0.3 dB. What is the worst-case margin?
Answer: 4.7 dB. Power budget = -3 - (-20) = 17 dB. Link loss = (18 x 0.5) + (2 x 0.75) + (6 x 0.3) = 9 + 1.5 + 1.8 = 12.3 dB. Margin = 17 - 12.3 = 4.7 dB. Choosing 12.3 dB confuses link loss with margin.
12. When preparing a worst-case optical power budget, which transmitter and receiver values should be used?
Answer: Minimum launch power and the sensitivity limit. A worst-case budget assumes the weakest transmitter (minimum launch power) and the least sensitive receiver (its specified sensitivity limit), then subtracts maximum component losses. Typical values make the margin look better than the link can guarantee. Overload matters only for short links with too little loss.
13. An OTDR test of a 40 km route cannot see the far end at a short pulse width. The tech switches to a much longer pulse. What is the trade-off?
Answer: More range, but longer dead zones and less resolution. A longer pulse puts more energy into the fiber, raising dynamic range so distant events show above the noise. The price is longer event and attenuation dead zones, so closely spaced events merge. Distance accuracy depends on the index setting, not the pulse width.
14. On a clean section of an OTDR trace at 1310 nm, cursors read 10.2 dB at 2.0 km and 12.0 dB at 7.0 km. What is the fiber attenuation, and does it meet a 0.5 dB/km outside plant limit?
Answer: 0.36 dB/km, meets. Attenuation is the level change divided by the distance between cursors: (12.0 - 10.2) / (7.0 - 2.0) = 1.8 / 5.0 = 0.36 dB/km, inside the 0.5 dB/km outside plant limit. Place both cursors on straight backscatter with no events between them. 1.8 dB is the section loss, not a per-kilometer value.
15. An analog CATV video link needs low total reflected power from all connectors and splices along it. Which instrument measures this directly?
Answer: Optical return loss test set. An ORL test set launches light and measures the total power reflected back from the whole link, giving optical return loss in dB. Analog video and high-speed lasers are sensitive to reflections. An OLTS measures insertion loss, a VFL finds breaks and bends, and an identifier detects live traffic.

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ETA FOT exam FAQ

How many questions are on the ETA FOT exam?

75 questions, with a time limit of 2 hours. Format: closed book; eta allows scratch paper and a non-programmable calculator. you must hold a current fiber optics installer (foi) certification and complete a special course and hands-on skills exam from an eta-approved school, so this prep covers only the written knowledge exam. eta does not publish the item format; our practice uses 4-option single-best-answer questions.

What is the passing score for ETA FOT?

75%.

How much does the ETA FOT exam cost?

US$155 exam fee (ETA list price); the course and hands-on assessment are priced by the school. One free retake within one year of the first session. Certification term 4 years, maintenance required. Offered as a stand-alone or Journeyman option (with the Associate CET). BICSI fees can change without notice, so confirm on bicsi.org before you apply.

Which languages is the ETA FOT exam offered in?

English. ETA does not say on its exam page whether other languages are offered; confirm with your Certification Administrator.

Where do I take the ETA FOT exam?

Taken through an ETA-approved school or trainer after its hands-on FOT course; the written exam is proctored by an ETA Certification Administrator, online through Trapeza or on paper.

Is this ETA FOT practice test free?

Yes. The 15-question practice test on this page is free, with an explanation for every answer and no signup. A free account also unlocks the complete study notes for the first topic. The full ETA FOT prep is Premium at $147 a month for this exam.

What's in the premium ETA FOT prep?

3,000 practice questions organized topic by topic (Transmission Principles, Light and Decibels: 375; Fiber Construction, Characteristics and Dispersion: 375; Safety, Cables and Installation: 375; Splicing and Connectors: 375; Sources, Detectors, Passive Components and WDM: 375; Passive Optical Networks: 375; Link Power Budgets and System Design: 375; OTDR, Loss Testing and Troubleshooting: 375), 6 full-length timed mock exams of 75 questions, 800 flashcards and 60 comprehensive key notes split across all 8 topics, plus a mistakes bank and the Readiness Score.

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Exam details are summarized from the official candidate information available in October 2026. BICSI changes formats and fees, so confirm with ETA International (Electronics Technicians Association, International); program accredited by ICAC to ISO/IEC 17024 before you book. RCDDQuizBank is not affiliated with BICSI or Pearson VUE.

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