Chapter 18 Calculating Illumination Levels
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1)
If a fixture 10 ft. above 2 ft2 surface provides 200 lumens on the surface, what is the illumination
level on the surface?
1) _______
A) 100 fc. B) 200 fc. C) 2 fc.
2)
If a point source with intensity of 200 candela is 10 ft. above a 2 ft2 surface, what is the
illumination level at the center of the surface?
2) _______
A) 200 fc. B) 2 fc. C) 100 fc.
3) Lux is the SI unit of illumination. Foot-candle is the IP unit. How are they related? 3) _______
A) 1 fc is about 100 lux. B) 1 fc is about 1000 lux. C) 1 fc is about 10 lux.
4) Which if the following are the two most significant components of Light Loss Factor (LLF)?
Select all that apply.
4) _______
A) Temperature factor. B) Lamp lumen depreciation factor.
C) Luminaire dirt depreciation factor. D) Lamp burnout factor.
5) Which of the following is a definition of coefficient of utilization (CU)? 5) _______
A) Foot-candle level on the task plane divided by total wattage of the system.
B) Lumens on the task plane divided by total wattage of the system.
C) Lumens on the task plane divided by total lumens of the lamps.
D) Total wattage of the lamps divided by total wattage of the system.
6) In order to use a manufacturer’s CU table, the designer must determine or assume which of the
following parameters? Select all that apply.
6) _______
A) Reflectance of ceiling cavity and floor cavity.
B) Wall reflectance.
C) Wall color.
D) Room cavity ratio.
7) If total lamp lumens is 10,000, CU is 0.50, and the task plane is 100 ft2, what will the illumination
level be?
7) _______
A) 50 foot-candles. B) 500 foot-candles. C) 5 foot-candles.
8) If the CU is 0.50, the design goal is 100 foot-candles, the task plane is 1000 ft2, how many fixtures
are needed if they each have 10,000 source lumens?
8) _______
A) 30 fixtures. B) 20 fixtures. C) 50 fixtures. D) 10 fixtures.
