Practice Test Geeks(CLD) Certified Lighting Designer Practice Test
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Photometry & Light Measurement Flashcards

7 cards from real CLD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Photometry & Light Measurement flashcards as text

  1. What unit is used to measure luminous flux?

    Answer: Lumen

    Luminous flux is measured in lumens (lm), representing the total quantity of visible light emitted by a source.

  2. Which unit measures illuminance, the amount of light falling on a surface?

    Answer: Lux

    Illuminance is measured in lux (lx) in SI units, representing lumens per square meter of surface area.

  3. A goniophotometer is primarily used to measure:

    Answer: Luminous intensity distribution of a luminaire

    A goniophotometer measures the luminous intensity distribution of a luminaire at various angles, producing photometric data used in lighting calculations.

  4. According to the inverse square law, if the distance from a point source doubles, the illuminance on a surface:

    Answer: Decreases to one-quarter

    The inverse square law states illuminance is inversely proportional to the square of the distance, so doubling the distance reduces illuminance to 1/4.

  5. Luminous intensity is measured in which unit?

    Answer: Candela

    Luminous intensity, which describes the power of a light source in a particular direction, is measured in candelas (cd), the SI base unit for photometry.

  6. What is the SI unit for luminance?

    Answer: Candela per square meter (cd/m²)

    Luminance, describing the perceived brightness of a surface as seen by the eye, is measured in candela per square meter (cd/m²), also called nits.

  7. The Color Rendering Index (CRI) is measured on a scale from 0 to:

    Answer: 100

    CRI is measured on a scale from 0 to 100, where 100 represents perfect color rendering equal to a reference illuminant such as daylight.

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