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Question 1

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According to Planck's radiation law, which of the following best describes the relationship between a blackbody's spectral emission and its temperature?

Total emitted power is proportional to the square of absolute temperature

Peak emission wavelength increases as temperature increases

Spectral radiance at every wavelength increases as temperature increases

A blackbody emits radiation only at a single characteristic wavelength

to track

2026 Statistics

Key Facts: IR Level I Exam

ε + ρ + τ = 1

Kirchhoff's Law

Fundamental radiation physics

T^4

Stefan-Boltzmann Power Law

Blackbody radiation

8–14 μm

LWIR Band (uncooled cameras)

IR spectral classification

70–80%

Min. Load for Electrical IR

ITC/Infraspection guidelines

10°C

Min. Delta-T for Building IR

ASTM E1186 / ITC guidelines

NFPA 70E

Arc-Flash Safety Standard

NFPA (National Fire Protection Association)

The Certified Infrared Thermographer Level I is the entry-level credential offered by ITC (Teledyne FLIR) and Infraspection Institute, both aligned with ASNT SNT-TC-1A and ISO 18436-7. Level I thermographers perform inspections under supervision of Level II or III personnel. The course covers Planck radiation law, Stefan-Boltzmann law, Wien's displacement law, emissivity, reflected apparent temperature, IFOV, NETD, qualitative electrical/mechanical/building inspections, NFPA 70E arc-flash safety, and basic reporting. Certification is valid for 3 years (Infraspection) or varies by provider.

Sample IR Level I Practice Questions

Try these sample questions to test your IR Level I exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1According to Planck's radiation law, which of the following best describes the relationship between a blackbody's spectral emission and its temperature?

A.Total emitted power is proportional to the square of absolute temperature

B.Peak emission wavelength increases as temperature increases

C.Spectral radiance at every wavelength increases as temperature increases

D.A blackbody emits radiation only at a single characteristic wavelength

Explanation: Planck's law defines spectral radiance as a function of both wavelength and temperature. As temperature increases, emitted power increases at every wavelength — the entire curve shifts upward. The Stefan-Boltzmann law summarizes this as total power proportional to T^4, and Wien's displacement law describes the shift of the peak to shorter wavelengths at higher temperatures.

2Wien's displacement law states that the peak wavelength of blackbody radiation is inversely proportional to absolute temperature. For an object at 300 K (approximately room temperature), the peak emission wavelength is approximately:

A.0.5 micrometers (visible green light)

B.2.0 micrometers (near-infrared)

C.9.7 micrometers (mid-wave infrared)

D.50 micrometers (far infrared)

Explanation: Wien's constant b ≈ 2898 μm·K. At 300 K: λ_peak = 2898 / 300 ≈ 9.66 μm, which falls in the mid-wave to long-wave infrared band (~8-14 μm). This is why thermal cameras designed for room-temperature targets use uncooled detectors sensitive in the 8-14 μm band.

3The Stefan-Boltzmann law states that the total radiant power emitted per unit area of a blackbody is:

A.Proportional to the absolute temperature

B.Proportional to the square of absolute temperature

C.Proportional to the fourth power of absolute temperature

D.Inversely proportional to absolute temperature

Explanation: The Stefan-Boltzmann law is expressed as M = σT^4, where σ (sigma) ≈ 5.67 × 10^-8 W/m²·K⁴ is the Stefan-Boltzmann constant and T is absolute temperature in Kelvin. Doubling the absolute temperature increases emitted power by a factor of 2^4 = 16.

4A perfect blackbody by definition has an emissivity of:

A.0.0

B.0.5

C.0.9

D.1.0

Explanation: A blackbody is a theoretical ideal that absorbs all incident radiation and emits the maximum possible radiation at a given temperature. Its emissivity ε = 1.0. Real objects (gray bodies or selective radiators) have emissivities between 0 and 1. Most painted or oxidized surfaces have emissivities of 0.85–0.95.

5When performing an infrared inspection of electrical switchgear, you measure a surface temperature of 65 °C on a bus bar connection that is at the same load as other connections measuring 30 °C. Which NETA/IEC standard temperature differential category does this represent?

A.Minor — temperature rise of 1–10 °C; monitor at next scheduled inspection

B.Intermediate — temperature rise of 11–20 °C; repair within one year

C.Serious — temperature rise of 21–40 °C; repair as soon as possible

D.Critical — temperature rise greater than 40 °C; repair immediately

Explanation: The temperature differential here is 65 – 30 = 35 °C. Per NETA and common Level I thermography severity criteria: 1–10 °C = monitor; 11–20 °C = increase surveillance or plan repair; 21–40 °C = repair as soon as possible (serious); >40 °C = immediately remove from service (critical). A 35 °C differential falls in the 'serious' range.

6Emissivity of a surface is defined as:

A.The fraction of incident radiation that is reflected by the surface

B.The ratio of radiation emitted by the surface to that emitted by a blackbody at the same temperature

C.The absolute amount of heat energy emitted per unit area per second

D.The ratio of absorbed to transmitted radiation

Explanation: Emissivity (ε) is a dimensionless ratio between 0 and 1 comparing actual emission from a real surface to the theoretical maximum (blackbody) emission at the same temperature. High emissivity surfaces (ε > 0.85) like painted metal radiate efficiently; polished metals have low emissivity (ε < 0.1) and appear deceptively cool in thermal images.

7A thermographer is imaging an uncoated, polished aluminum heat sink with an emissivity of approximately 0.05. Without correcting emissivity on the camera, the displayed temperature reading will be:

A.Approximately correct because aluminum conducts heat well

B.Significantly higher than the actual surface temperature

C.Significantly lower than the actual surface temperature

D.Unaffected because cameras compensate for emissivity automatically

Explanation: At ε = 0.05, the aluminum emits only 5% of what a blackbody would at the same temperature. The camera, calibrated for blackbody emission, interprets this low signal as a much cooler surface. The camera will display a temperature far below the actual surface temperature. The surface is actually reflecting the cool (ambient) background, compounding the error.

8Reflected apparent temperature (RAT) in thermography refers to:

A.The temperature of the camera detector array

B.The temperature that the surface appears to emit due to reflected background radiation

C.The temperature rise caused by solar loading on an outdoor surface

D.The ambient air temperature used to correct for convective cooling

Explanation: Reflected apparent temperature (also called reflected temperature or background temperature) is the apparent contribution from reflected ambient radiation that reaches the camera from the target surface. For low-emissivity surfaces, this contribution dominates the total signal. Accurate thermography requires measuring the RAT (often with a crumpled aluminum foil target) and entering it into the camera's radiometric formula.

9Instantaneous Field of View (IFOV) is the primary specification used to determine a thermal camera's:

A.Temperature measurement range

B.Thermal sensitivity (NETD)

C.Spatial resolution — the smallest object reliably resolved at a given distance

D.Maximum frame capture rate

Explanation: IFOV (Instantaneous Field of View) is the angular size of a single detector pixel, typically expressed in milliradians (mrad). It determines spatial resolution: a smaller IFOV means finer detail can be resolved. At a given distance D, the minimum resolvable spot size ≈ IFOV × D. For quantitative temperature measurement, the target should fill at least the MFOV (Measurement Field of View), often 3× the IFOV.

10Noise-Equivalent Temperature Difference (NETD) is the specification that describes a thermal camera's:

A.Spatial resolution — the smallest object the camera can detect

B.Thermal sensitivity — the smallest temperature difference the camera can detect

C.Maximum operating temperature range

D.Accuracy of radiometric temperature measurements

Explanation: NETD (Noise-Equivalent Temperature Difference), expressed in milli-Kelvin (mK), is the minimum temperature difference the detector can distinguish from electronic noise. A camera with NETD = 30 mK can detect temperature differences as small as 0.03 °C under ideal conditions. Lower NETD values indicate better thermal sensitivity, enabling detection of subtle thermal anomalies.

About the IR Level I Exam

The Certified Infrared Thermographer Level I credential is the entry-level certification for professional thermographers. Offered by the Infrared Training Center (ITC, Teledyne FLIR) and Infraspection Institute, both aligned with ASNT SNT-TC-1A and ISO 18436-7, it validates foundational competency in infrared theory, camera operation, qualitative inspection of electrical systems, mechanical equipment, and building envelopes, and safe working practices under NFPA 70E.

Questions

100 scored questions

Time Limit

Typically 2–3 hours (written exam, varies by provider)

Passing Score

Not publicly disclosed (typically ~75%)

Exam Fee

Included in Level I course fee; contact infraredtraining.com or infraspection.com for current pricing (Infrared Training Center (ITC, Teledyne FLIR) and Infraspection Institute)

IR Level I Exam Content Outline

20%

Infrared Theory and Physics

Blackbody radiation, Planck's law, Stefan-Boltzmann law, Wien's displacement law, emissivity, reflectivity, transmissivity, Kirchhoff's law, gray body vs. selective radiator

20%

Infrared Camera Operation

IFOV, NETD, FOV, lens selection, detector types (microbolometer), NUC, level/span, color palettes, spot/area measurement tools, D:S ratio, atmospheric attenuation, IR-opaque materials

20%

Electrical System Inspection

Load requirements (70–80% minimum), temperature differential severity criteria, switchgear/panel/busway/transformer/overhead line inspection, connection defects, three-phase comparison

15%

Mechanical Equipment Inspection

Bearing inspection, motor winding patterns, coupling misalignment, steam trap analysis, refractory monitoring

15%

Building Envelope Inspection

Delta-T requirements, insulation defects, thermal bridges, air infiltration patterns, rooftop wet insulation (thermal capacitance method), interior vs. exterior surveys

10%

Safety, Certification, and Reporting

NFPA 70E arc-flash PPE, approach boundaries, ASNT SNT-TC-1A Level I responsibilities, ISO 18436-7, Infraspection IISE standard, inspection report elements, data management

How to Pass the IR Level I Exam

What You Need to Know

Passing score: Not publicly disclosed (typically ~75%)
Exam length: 100 questions
Time limit: Typically 2–3 hours (written exam, varies by provider)
Exam fee: Included in Level I course fee; contact infraredtraining.com or infraspection.com for current pricing

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

IR Level I Study Tips from Top Performers

1Master the four infrared physics laws: Planck (spectral emission), Stefan-Boltzmann (total power ∝ T^4), Wien's displacement (peak wavelength = 2898/T μm), and Kirchhoff's law (ε + ρ + τ = 1)

2Remember emissivity rules: painted surfaces ε ≈ 0.85–0.95, bare polished metals ε ≈ 0.02–0.10 — and visible color has NO reliable relationship to LWIR emissivity

3Know camera specifications: IFOV = angular size of one pixel (spatial resolution), NETD = minimum detectable temperature difference (sensitivity), FOV = total angular coverage of scene

4For electrical inspections, require 70–80% load minimum and compare similar components under similar loads — temperature differential, not absolute temperature, is the primary diagnostic tool

5For building envelope surveys, require at least 10°C delta-T between interior and exterior; rooftop wet insulation surveys are best 1–4 hours after sunset

6Know NFPA 70E arc-flash boundaries and PPE requirements — the thermographer's minimum approach distance is set by the incident energy analysis, not camera optics

7Level I responsibilities: perform surveys and record data under Level II/III supervision; cannot independently evaluate results or write procedures

Frequently Asked Questions

What is the Certified Infrared Thermographer Level I certification?

The Certified Infrared Thermographer Level I is the entry-level thermography credential offered by the Infrared Training Center (ITC, a division of Teledyne FLIR) and Infraspection Institute. Both programs align with ASNT SNT-TC-1A and ISO 18436-7. Level I thermographers are qualified to perform calibrated setup, conduct infrared surveys, and record data under the direct supervision of a Level II or Level III thermographer. The credential is used in electrical predictive maintenance, building diagnostics, and mechanical condition monitoring.

What topics are covered in the Level I thermography exam?

Level I thermography covers: infrared physics (Planck's law, Stefan-Boltzmann law, Wien's displacement law), emissivity and reflected apparent temperature, thermal camera operation (IFOV, NETD, FOV, microbolometer detectors, NUC), qualitative electrical inspection (load requirements, severity criteria, switchgear, transformers), mechanical inspection (bearings, motors, steam traps), building envelope (insulation defects, thermal bridges, rooftop surveys), NFPA 70E electrical safety, and ASNT SNT-TC-1A certification framework.

What is the difference between ITC Level I and Infraspection Institute Level I?

Both ITC (Infrared Training Center, Teledyne FLIR) and Infraspection Institute offer Level I thermography certifications aligned with ASNT SNT-TC-1A and ISO 18436-7. ITC courses are closely associated with FLIR camera training but cover all manufacturers' equipment. Infraspection Institute is an independent organization that developed the Infraspection Standard for Infrared Inspection of Electrical Systems (IISE) and related standards. Both credentials are respected throughout the industry. ITC courses are available globally through partner training centers.

How long is the Level I thermography certification valid?

Infraspection Institute Level I certifications are valid for 3 years and require renewal with documented experience and continuing education. ITC's certification validity and renewal requirements vary; check with ITC directly at infraredtraining.com. ASNT SNT-TC-1A employer-based certifications have validity periods defined in each employer's written practice — typically 3–5 years with recertification requirements.

What are the responsibilities of a Level I thermographer under ASNT SNT-TC-1A?

Per ASNT SNT-TC-1A, a Level I thermographer can: set up and calibrate equipment using established procedures, perform specific inspections per written procedures, record data and results. A Level I cannot independently evaluate or classify results, make final accept/reject decisions, establish new procedures, or approve written practices. All Level I work must be supervised by a Level II or Level III certified thermographer.

What safety standards apply to infrared electrical inspections?

NFPA 70E (Standard for Electrical Safety in the Workplace) is the primary safety standard governing electrical IR inspections. It requires: an arc-flash risk assessment, establishment of arc-flash and approach boundaries, arc-rated PPE matched to the incident energy for each piece of equipment, and an energized electrical work permit when working inside the restricted approach boundary. Thermographers should also consult the Infraspection Institute Standard for Infrared Inspection of Electrical Systems (IISE) for inspection methodology and severity criteria.

How do I prepare for the Level I thermography written examination?

Prepare by mastering: infrared physics fundamentals (Planck, Stefan-Boltzmann, Wien, emissivity, Kirchhoff's law), camera specifications (IFOV, NETD, NUC, level/span, D:S ratio), measurement technique (emissivity correction, RAT measurement, atmospheric correction), qualitative inspection patterns for electrical, mechanical, and building applications, NFPA 70E safety requirements, and the ASNT SNT-TC-1A Level I/II/III responsibility structure. Practice with our 100 free questions covering all Level I topic areas.