BS: Lesson 7 - Lighting

Question 0

What is the visible spectrum of light the human eye can see?

Answer 0

wavelengths of +/- 380 - 780 nanometers

Question 1

The eye is composed of which three parts?

Answer 1

lens

iris

retina

Question 2

The direct light that falls on a subject is called?

Answer 2

incident light

Question 3

What is a reflection of incident light that partially or totally obscures the details to be seen on a surface by reducing the constrasts?

Answer 3

veiling reflections or reflected glare

Question 4

The CRI (color rendition index) is use to?

Answer 4

measure how well light actually shows true color

Question 5

Name two methods to measure how true white is.

Answer 5

CRI (color rendition index)

color temperature

Question 6

Define flux

Answer 6

Flux or luminous flux is the measure of the perceived power or quality of light; measured in lumens. The luminous energy of the light source.

Question 7

What is the difference between illumination and luminance?

Answer 7

Illumination is the density of luminous power, expressed in terms of lumens per area.

Luminance is a photometric measure of the luminous intensity per unit of area light traveling in a given direction. It describes the amount of light that passes through or is emitted from a particular area and falls within a given solid angle - how bright it looks.

Question 8

What term would you use to characterize emission or reflection from flat, diffused surfaces?

luminance
luminous flux
illumination
brightness

Answer 8

luminance

Question 9

Doubling the distance from the source and reciever of a light source does what to the illumination?

Answer 9

cuts the illumination to 1/4

Question 10

Which light bulb shapes have an interior reflector?

Answer 10

R and PAR

Question 11

The metal back on the light filament helps to ________.

Answer 11

Extend the life of the lamp, slightly.

Question 12

Running a lamp at hight temperatures produces more

illumination and glare
energy and power
heat and energy
light and color

Answer 12

light and slightly better color

Question 13

The lifetime of a flourescent bulb depends on ________.

Answer 13

number of hours lit

the number of times it is turned on/off

Question 14

A point grid method for calculating lighting levels is used when?

Answer 14

for a single fixture, or small number of fixtures, and takes into account orientation and distance.

Question 15

What is Abney’s Law?

Answer 15

The light light arriving at a surface is the sum of the light arriving from all of the sources (not including reflected light).

Question 16

The zonal cavity method is based on _________.

Answer 16

a uniform distribution of a large number of fixtures, takes into account the reflected light, and is used mostly in commercial and factory spaces.

Question 17

The amount of light required to see well is affected by?

Answer 17

age of observer

task at hand

how diffused the light is

Question 18

Equivalent Spherical Illumination (ESI) is

Answer 18

optimum light that is based on a theoretical sphere surrounding the object being illuminated - used to reduce contrast and measure glare.

Question 19

Footcandle is a measure of

Answer 19

illumination

Question 20

candlepower is a measure of

Answer 20

the power at the source

Question 21

Lumen is a measurement of?

Answer 21

flux

Question 22

footLambert measures?

Answer 22

reflected or transmitted brightness