ETech Lighting Exam

What is the layered approach in lighting design?

a strategy that combines multiple types of lighting (ambient light, task lighting, accent lighting, decorative lighting)

What are the advantages to a layered approach in lighting design?

ambient luminescence, focal glow, brilliance, balance

What are the considered aspects in determining the CU of a fixture?

room cavity ratio, surface reflectance, lamp luminaire characteristics

Which light source is most likely represented by this spectral distribution curve?

high pressure sodium

What is the visible portion of the electromagnetic wave spectrum?

380-780 nanometers

Why is an LED lamp typically fitted with heat sink?

the electric junction cannot be allowed to excessively overheat

Which lamp has the highest luminous efficacy?

LED (lm/watts)

What are the privileges of LED lamps over fluorescent lamps?

energy efficiency, long life span, don’t put off heat

What is the threshold minimum value and acceptable visual comfort probability?

70%

What is the difference between maintained illuminance and initial illuminance in the use for the lumen method?

initial illuminance is the illuminance of a new light source while maintained illuminance is over time with use

CT - Color Temperature

a scale to measure color appearance of light expressed in degrees Kelvin

What would be a useful reference in specifying a light source for a clothing store display?

the CRI and the CCT of a lamp

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

brown

What is the height of the surface considered equal to in designing a store dedicated to carpet displays at floor level?

0

What types of light are these photometric webs

a. indirect b. direct-indirect

What is the diameter of a lamp represented in?

1/8”

Which lamp requires a driver instead of a ballast?

LED

What units is the intensity of light in a particular direction expressed in?

candelas

What is one space scenario for which a dark ceiling surface is desirable?

a theater to minimize light reflection and glare

What is the luminous intensity of light at 15 degrees from the vertical line?

~9000

Efficacy

how efficiently a light source produces visible light in lm/watts

Driver

LEDs use these in place of ballasts to regulate and convert power

What unit is luminance measured in?

candela per square meters (cd/m²)

What unit is illuminance measured in?

lux/lumen per square meters (lm/m²)

Luminous Intensity Unit

candela (cd)

Luminous Flux Unit

lumen (lm)

VCP - Visual Comfort Probabillity

a metric used in evaluating the issue of direct glare (higher number = less glare)

Cones vs. Rods

cones are color perception while rods are value

Color Temperature

measured in kelvin, describes the warmth/coolness of light (higher = cooler, lower = warmer)

CCT

perceived color of light source not specific to black body radiators

CRI - Color Rendering Index

how accurately a light source displays the color of an object compared to natural light measured from 1-100 (80+ is acceptable)

What are the primary colors in white light?

red, green, blue

What are the percentages of light distribution for direct, direct indirect, semi direct, and semi indirect?

What is the diameter of an A19 lamp?

19/8=2.375

LLF - Light Loss Factor

quantifies the reduction in illuminance of a lighting system over time (lumen depreciation, dirt buildup, room surface depreciation)