Lighting Flashcards
Which part of the eye is the:
a. light-sensitive surface where the image is projected onto at the back of the eye
b. coloured portion that functions as a diaphragm to control the amount of light entering the eye
c. opening in the centre of the is where light enters the eye
d. transparent capsule behind the iris that is used to focus the image
A) Retina
B) Iris
C) Pupil
D) Lens
State the four main factors considered to affect visibility.
Size , brightness, contrast, Time
Which one of the preceding factors is most important when viewing moving objects?
Time
What two important features does a good lighting system provide?
Brightness, Contrast
Using the electromagnetic spectrum, which is the higher frequency light: infrared or ultraviolet
Ultraviolet
The actual colour composition of white light can be seen using a
Prism
The human eye is considered to be most responsive to colour range of:
a. purple
b. red
c. orange-red
D. yellow-green
Yellow-Green
- The “colour” of light is determined by its
Wavelength
The total light output of a lamp is measured in
Lumens
The unit for illumination is the
Lux (Lx) EV
What two values does efficacy compare?
light output (lumens)
and pover input
Which of the following types of lamps is considered to provide the best colour rendition?
a. incandescent
b. mercury vapour
c. high-pressure sodium
d. fluorescent -cool white
Incandescent
Which of the following light sources is generally considered as having the highest efficacy?
a. incandescent
b. fluorescent
c. mercury vapour
d. high-pressure sodium
High Pressure Sodium
The lighting level on a work plane is commonly measured using a
Photometre
In simple terms, state what is meant by the:
A) Inverse square law
B) Cosine law
A) Illumination is inversly proportional to the square of distance between them
B) The ilumination of any surface varies as the cosie of the angle of incidence, Angle of incidence is between the normal to the surface and the direction of incident light
- When referring to wavelengths of light, what is a nanometre?
A nanometre is one billionth
of a metre
The two main factors in the design of a lighting system involve both the
Quantity of light and quality of light
- List three variables (factors) involved in the design of a lighting installation.
Area and type of enviourment (indoors or outdoors)
Type of Task (critical seeing or decoration)
Architectural requirements
Costs of installation
Availability
Environmental impact
What are three factors that contribute to the quality of light?
Glare
Diffusion
Colour
What two colours are considered to be “cooling”?
Blue and green
A complete lighting unit (lamps, reflectors, etc.) is called a
Luminaire
What does a distribution curve illustrate?
The variation in light density, usually througha vertical axis
What are two important considerations for roadway lighting design?
CRI, and light level
What lamp type does not start (light up) immediately?
HID High Intesity Discharge
What are the two main causes of light loss over time?
Lamp lumen depreciation
Luminaire dirt depreciation
Why is group relamping usually recommended?
Minimize disruptions and labour costs
Luminaire efficiency
The percentage of total lumens emmited by the luminaire compered do the total lumens geneated by the lamp alone
Coefficient of utilization
The percentage of lamp lumens that actually reach the area for lighting
What is the essential difference between direct and indirect classifications of luminaires?
Direct = 0-10%: upward componet and indirect 90-100% upward
How is light produced in an incandescent lamp?
Passing electric curent through, filament and heating until it glows
What percentage of the output of an incandescent lamp is in the form of light? What percentage is in the form of heat?
10% is light
90% heat
As a light-producing device, the incandescent lamp is:
a. highly efficient
b. moderately efficient
c. very inefficient
Very Inefficient
- What types of gas are used in incandescent lamps, and for what purpose?
Argorn and nitrate
A 100 W incandescent lamp is designated as G25 on the box. What is the shape and diameter of this lamp
Globular 3-1/8
Where would you likely locate information about the overall length of a lamp?
In the manufacturer’s catalogue
What material is the filament normally made of?
Tungsten
Why are heat deflectors used in some lamps?
To deflect heat from base area, where it may losen the cement
The glass in lamps used for general purposes is
a. clear
b. diffuse
c. coloured
Diffuse
- Why is the glass identified in the previous question used for general purpose
Diffuce glass reduces the brightness of the light source by effectively incresing the surface area of the bulb (reduce glare)
The melting point of tungsten is closest to:
3500
How does a green incandescent lamp produce that colour light?
other colours are absorted by glass, only green is let out
The most common lamp base is the
screw type or edison base
Name a typical application for each of the following lamp bases:
a. mogul
b. prefocus
c. three-contact screw base
high wattage lamps = mogul
Projector lamps = prefocus
Trilight lamps = three-contact screw base
The higher the temperature of the lamp filament, the output and the. lamp life.
Higher the light and lower the lamp life
What normally ends the life of an incandescent lamp?
evaporation of the Filament reduces the filament diameter to the breaking point, end of life occurs when the filement finally breaks
Lumen maintenance or maintained lumens are highest when a general service lamp is operated
With the base up
State a reason why the light output of an incandescent diminishes over the life of the lamp.
Tungsten evaporating From the filament sticks to the inside of the glass bulb and blocks percentage of light emmissions
Which of the following combinations of incandescent lamps produces the most light
One 150 W
For the same wattage, which lamp would last longer, a 120 V or a 12 V?
12 Volt
Another name for the tungsten-halogen lamp is the
Quartz halogen
lamp.
What is the regenerative cycle action in the tungsten-halogen lamp
Evaporated Tungsten from the filament combining with the halogen and being redeposited in the filament
Explain why a tungsten halogen lamp has high lumen maintenance compared to a standard incandescent
wall blackening reduces light output , so that’s why lumen maintenance is higher in tungsten halogen incandescent
Typical lamp life of a typical 1500 W tungsten-halogen lamp would be closest to
2500 hours
What feature of quartz glass makes it suitable for the tungsten-halogen lamp?
High melting temperature
Why must the tungsten-halogen lamp be enclosed in a reflector or similar enclosure?
The possibility of the lamp shattering at normal end of life
The dominant colour of the light from a tungsten-halogen source is
White
Why is continuous dimming not recommended for tungsten-halogen lamp
Reduced temperature may prevent the regenerative cycle action
What condition is finger contact with cold quartz glass likely to cause?
Premature glass breakage and/or glass discolouration
Why must tungsten-halogen lamps be de-energized before installation or replacement?
Severe burns if skin contact is made
Explain the lamp designation MR16.
multi Faceted reflector 16/ 8th” inches
What type of light source is LED lighting?
Electrochemical
What is the approximate efficacy of LED lighting?
75-150 lumens/Watt
List four advantages of LED lighting.
Low power consumption
Available in all colours
Fully dimmable
Resistant to damage from shock and vibration
List three disadvantages of LED lighting.
More expensive
Very heat sensitive
Typically cast light in one direction
List four applications for LED lighting.
Traffic Signal lamps
Exit Signs
Road lights
Security lighting
