Practice Test Geeks(CLC) Certified Lighting Consultant Practice Test
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Light Source Technology & LEDs Flashcards

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

Read the first 7 Light Source Technology & LEDs flashcards as text

  1. What is the significance of the 'forward voltage (Vf)' specification on an LED datasheet?

    Answer: It is the voltage drop across the LED junction at its rated operating current

    Forward voltage is the voltage drop across the LED at its specified operating current; it varies with junction temperature and is critical for driver design.

  2. Organic LEDs (OLEDs) differ from inorganic LEDs primarily in that they:

    Answer: Emit light from a thin organic carbon-based film rather than a crystalline semiconductor chip

    OLEDs use organic (carbon-based) electroluminescent materials deposited in thin layers, producing a diffuse, large-area light source unlike the point-source nature of inorganic LEDs.

  3. A lighting designer specifies a Duv value of +0.002 for a hospitality project. What does a positive Duv indicate?

    Answer: The chromaticity is slightly above (greener than) the blackbody locus

    Duv measures distance from the Planckian (blackbody) locus; positive values indicate the chromaticity is above the locus toward green, while negative values indicate below toward magenta/pink.

  4. Which of the following best describes 'human centric lighting' (HCL) in relation to LED technology?

    Answer: Using tunable LED systems to support circadian rhythms by varying CCT and intensity throughout the day

    Human centric lighting leverages tunable LED technology to vary color temperature and light levels to align with natural circadian rhythms and support health and wellbeing.

  5. What is 'luminous efficacy of radiation' (LER), and how does it differ from source efficacy?

    Answer: LER is the ratio of lumens to radiated watts of the spectrum (max 683 lm/W); source efficacy includes electrical input losses

    LER quantifies how well the spectral power distribution of a source converts radiant power to lumens (peak 683 lm/W at 555 nm); source efficacy includes driver and thermal losses from input watts.

  6. Which standard governs the LM-80 lumen maintenance testing protocol for LED packages, arrays, and modules?

    Answer: ANSI/IES LM-80

    ANSI/IES LM-80 defines the approved method for measuring lumen maintenance of LED packages, arrays, and modules over a minimum 6,000-hour test period.

  7. A lighting consultant recommends a luminaire with an R9 value of 72. In which application would this specification be LEAST critical?

    Answer: Industrial warehouse aisle lighting

    Warehouse aisle lighting primarily requires adequate illuminance for task visibility and safety; high R9 (saturated red rendering) is far less critical than in food retail, medical, or photography settings.