COLORADO PHOTOMETRY TECHNICIAN
CERTIFICATION EXAM QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) Q&A 2026
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1. What is photometry primarily used to measure?
A. Heat energy
B. Light intensity as perceived by the human eye
C. Electrical resistance
D. Sound waves
Correct Answer: B. Light intensity as perceived by the human
eye
Rationale: Photometry measures visible light as perceived by
human vision, unlike radiometry which measures all
electromagnetic radiation.
2. Which unit is commonly used in photometry for luminous
intensity?
A. Watt
B. Joule
C. Candela
D. Lux
Correct Answer: C. Candela
Rationale: Candela is the SI base unit for luminous intensity in a
specific direction.
,3. Lux is a measure of:
A. Luminous flux
B. Luminous intensity
C. Illuminance
D. Radiant energy
Correct Answer: C. Illuminance
Rationale: Lux measures luminous flux per unit area (lumens
per square meter).
4. Lumen measures:
A. Light emitted by a source
B. Light absorbed by a surface
C. Electrical power
D. Temperature of light
Correct Answer: A. Light emitted by a source
Rationale: Lumen measures total visible light output from a
source.
5. Which device is commonly used to measure light intensity?
A. Spectrometer
B. Photometer
C. Barometer
D. Ammeter
Correct Answer: B. Photometer
,Rationale: A photometer measures luminous intensity or
brightness.
6. What does illuminance refer to?
A. Light emitted from a source
B. Light falling on a surface
C. Heat from light
D. Frequency of light waves
Correct Answer: B. Light falling on a surface
Rationale: Illuminance is the amount of light incident on a
surface per unit area.
7. The SI unit of illuminance is:
A. Candela
B. Lux
C. Watt
D. Lumen
Correct Answer: B. Lux
Rationale: Lux equals lumens per square meter.
8. Which of the following best describes luminous flux?
A. Light per unit time perceived by humans
B. Total visible light output from a source
C. Resistance to light flow
D. Energy stored in light
, Correct Answer: B. Total visible light output from a source
Rationale: Luminous flux is the total perceived power of light
emitted.
9. What is the main difference between photometry and
radiometry?
A. Photometry measures sound
B. Radiometry ignores light
C. Photometry considers human eye sensitivity
D. Radiometry is only for visible light
Correct Answer: C. Photometry considers human eye sensitivity
Rationale: Photometry weights light according to human vision
response.
10. The human eye is most sensitive to light in which range?
A. Infrared
B. Ultraviolet
C. Green-yellow region
D. Red region
Correct Answer: C. Green-yellow region
Rationale: Peak sensitivity is around 555 nm (green-yellow
light).
11. Which color has the longest wavelength in visible light?
A. Blue
CERTIFICATION EXAM QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) Q&A 2026
|INSTANT DOWNLOAD PDF
1. What is photometry primarily used to measure?
A. Heat energy
B. Light intensity as perceived by the human eye
C. Electrical resistance
D. Sound waves
Correct Answer: B. Light intensity as perceived by the human
eye
Rationale: Photometry measures visible light as perceived by
human vision, unlike radiometry which measures all
electromagnetic radiation.
2. Which unit is commonly used in photometry for luminous
intensity?
A. Watt
B. Joule
C. Candela
D. Lux
Correct Answer: C. Candela
Rationale: Candela is the SI base unit for luminous intensity in a
specific direction.
,3. Lux is a measure of:
A. Luminous flux
B. Luminous intensity
C. Illuminance
D. Radiant energy
Correct Answer: C. Illuminance
Rationale: Lux measures luminous flux per unit area (lumens
per square meter).
4. Lumen measures:
A. Light emitted by a source
B. Light absorbed by a surface
C. Electrical power
D. Temperature of light
Correct Answer: A. Light emitted by a source
Rationale: Lumen measures total visible light output from a
source.
5. Which device is commonly used to measure light intensity?
A. Spectrometer
B. Photometer
C. Barometer
D. Ammeter
Correct Answer: B. Photometer
,Rationale: A photometer measures luminous intensity or
brightness.
6. What does illuminance refer to?
A. Light emitted from a source
B. Light falling on a surface
C. Heat from light
D. Frequency of light waves
Correct Answer: B. Light falling on a surface
Rationale: Illuminance is the amount of light incident on a
surface per unit area.
7. The SI unit of illuminance is:
A. Candela
B. Lux
C. Watt
D. Lumen
Correct Answer: B. Lux
Rationale: Lux equals lumens per square meter.
8. Which of the following best describes luminous flux?
A. Light per unit time perceived by humans
B. Total visible light output from a source
C. Resistance to light flow
D. Energy stored in light
, Correct Answer: B. Total visible light output from a source
Rationale: Luminous flux is the total perceived power of light
emitted.
9. What is the main difference between photometry and
radiometry?
A. Photometry measures sound
B. Radiometry ignores light
C. Photometry considers human eye sensitivity
D. Radiometry is only for visible light
Correct Answer: C. Photometry considers human eye sensitivity
Rationale: Photometry weights light according to human vision
response.
10. The human eye is most sensitive to light in which range?
A. Infrared
B. Ultraviolet
C. Green-yellow region
D. Red region
Correct Answer: C. Green-yellow region
Rationale: Peak sensitivity is around 555 nm (green-yellow
light).
11. Which color has the longest wavelength in visible light?
A. Blue
