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R1 > LT1-5 > Flashcards

LT1-5 Flashcards

1
Q

Light enters through the ___?

A

Cornea

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2
Q

What does the retina do?

A

Forms the optical image

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3
Q

WHat are 4 factors that affect visiblilty

A

Size, brightness, contrast, time

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4
Q

poor lighting causes the eye muscles to become ___

A

Tired and fatigued

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5
Q

A good lighting system provides

A

the quantity, and the quality of light ​

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6
Q

Different colours are actually different ____

A

Wave lengths

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7
Q

What is coulour temperature measured in

A

Kelvin

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8
Q

Below 3000K is ______ lIght

A

soft, warm light

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9
Q

Above 4000K is ______ light

A

Hard, cold light

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10
Q

CRI stands for

A

Colour Rendering Index

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11
Q

What is a definiton of CRI

A

“The ability of a light source to portray the colour appearance of objects accurately when compared to a standard (reference) light source of the same colour temperature.”​

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12
Q

Does Low -preassure sodium lighting have a really good or bad CRI

A

Really bad, its undefined

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13
Q

What is total quantity from a light source called and measured in?

A

Luminous flux, measured in Lumens

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14
Q

What is Illumination or lighting level on a surface called and measured in?

A

Called luminous flux density, measured in Lux

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15
Q

What is the device that measures lighting levels called

A

A photometer

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16
Q

What is luminous efficacy the ratio of ?

A

he ratio of the light output (lumens), to the power input (watts)​

17
Q

How many lumens in 1 watt for 100% effeciency

A

683 lumens per watt

18
Q

What are some factors in lighting choices (6)

A

Area and type of environment ​

Type of task ​

Architectural and decorative requirements ​

Costs of operation​

Availability ​

Environmental impact

19
Q

Factors of quality of light (3)

A

Glare, diffusion, colour

20
Q

What is a complete lighting unit called

A

Luminaire

21
Q

Four different light sources for luminaires

A

Incandescent​

Fluorescent ​

High-intensity discharge (HID)​

LED

22
Q

Lamps should be replaced at what % of their rated life

A

70%

23
Q

WHy is it important to clean light fixtures

A

can add 30% more light…making sure ventilation is good

24
Q

Why are incadecents bulbs bad

A

90% of energy is wasted in heat

25
Q

What is the filament in a incandescent usually made out of and why

A

tungsten, very high melting point of 3419 degrees Celsius​

Low rate of evaporation

26
Q

WHat do the number on light bulb sizes mean?

A

The max width measured in 1/8ths of and inch
ex: 10 = Size = 10x1/8” or 1 ¼”

27
Q

3 different bulb glass

A

Clear, diffuse, couloured

28
Q

what is the normal lightbulb base called

A

Medium Edison bass

29
Q

How many watt can a medium bass handle

A

7.5-300w

30
Q

What is the next size up from medium bass

A

Mogul

31
Q
A
32
Q

Do incandescent lights draw more or less current when they are cold

A

More. It draws more current than when it is warm due to a low
initial filament resistance

33
Q

What does LED stand for

A

Light emitting diode

34
Q

Efficacy of led ( lumens per watt)

A

75-150 lumens per watt

35
Q

Efficacy of incandescent ( lumens per watt)

A

22 lumens per watt

36
Q

Advantages of LEDs

A

Low power consumption
• Negligible early installation failures
• Resistant to shock and vibration…no glass or filament to break
• LEDs are fully dimmable
• Available in all colours
• LEDs are cool when operating
• They are extra low-voltage
• Unwanted light does not bleed off
• Deliver directed light for increased system efficiency

No moving parts, no toxic gases, no filament to burn, break
or fail…nothing that will contaminate the environment
• Small size
• Extremely long service life (50 000 hours or more)
• Instant on/off in their operation
• Work well in cold weather….works well from -40 degrees to
185 degrees
• LEDs have an acceptable colour redering index…around 70

37
Q

Disadvantages of leds

A

More expensive
• Very heat sensitive
• Reflectors or lenses are needed to disperse the light

R1 (1 decks)

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