EXAM 3- ETECH LIGHTING

Describe the layered approach in lighting design and identify its advantages

layered approach uses general illumination, task lighting, and accent lighting in combination to serve various needs

In determining the CU of a fixture, two of the three considered aspects are:

room geometry, material reflectance, luminaire itself

Which light source is most likely represented by this special distribution curve

High Pressure Sodium

The visible portion of the electromagnetic wave spectrum lies between:

380-780 nanometers

The LED lamp is typically fitted with a heat sink because:

The electric junction cannot be allowed to excessively overheat

Which of the 3 lamps has the highest luminous efficacy?

LED / Lumens per watt (Lm/W)

Give 2 specific reasons that privilege the use LED lamps in comparsion to fluorescent lamps

Efficient, longer life span

The visual comfort probability is an index indicating the potential effect of glare. The threshold (minimum) value for an acceptable VCP is __

70%

Explain the difference between maintained illuminance and initial illiuminance in their use for the Lumen method

Maintained illuminance is the fixtures illuminance throughout its life span. Initial upon first use E=Initial E x LLF. (LLF is how maintained E is calculated)

CT is…... ?

A scale to measure color appearance of light expressed in degree Kelvin

In specifying a light source for clothing store display..?

The CRI and CCT of a lamp would be useful references

If a red car is parked under high pressure sodium lamps, the perceived color is

Brown

In designing a store dedicated to carpets display at floor level, the height of the surface is considered equal to ______

The floor

Examine the 2 photometric webs below, and match them to the corresponding type indicated below

Direct: (none)

Direct-Indirect: (b)

Indirect-Direct: (none)

Indirect: (a)

The diameter of lamps is represented in…?

1/8th of an inch

Which of the following lamps require a driver instead of a ballast

LED

The intensity of light in a particular direction is expressed in unit called…?

Candelas

Consider 2 lamp fixtures (2PMO 2 32 27LS) installed in a classroom with H=10’00" W=25’00” L=45’00”. Determine the number of fixtures needed to illuminate at 50fc. RCR=4, effective ceiling cavity reflectance = 80% effective floor cavity reflectance=20% wall reflectance=70% LLF=0.65 and lumens produced by each lamp=3000

(#) of Luminaires = ( E x AREA) / (Lamps per luminaire x CU x LLF x Lumens per lamp) = 25 fixtures

In general, ceilings are bright surfaces. Identify one space scenario for which a dark ceiling surface is desirable

Movie Theaters, Resturaunts, Auditorium spaces

From the photometric web below, give the luminous intensity of light at 15 degrees from the vertical line

9000 Candelas