illumination final exam

A wall grazer is the same as an wall washer

False

In the IES TM-30 system, the R(g) metric has a range of values from 0 to 100.

False

Luminous flux expresses the lumens from a source going in a particular direction and has units of candelas or candlepower.

False

Research shows that we have a preference for red saturation. The more saturated the color the more we like it.

False

Wall luminaires when directed downwards can act as floor washers

True

Exitance

W/m^2

Ultrasonic occupancy sensors require a direct line of sight to the motion being detected to work properly.

false

Illuminance

fc or lux

The dark wood floor in a lobby has 80% absorptance. If 100 lumens strike the floor from a window, how many lumens from that window are reflected from the floor into the lobby?

the properties of the window are needed to answer the question

High pressure sodium lamps are known for producing a very warm color tone of light.

true

In general, people prefer colors that are more saturated than they appear under the reference light source.

true

The phosphor coating on a fluorescent lamp absorbs UV energy and produces visible light.

true

Which of the following best describes how an LED light source creates light?

Electricity flows across a P-N junction

The term "shielding angle" when used for luminaires refers to which of the following?

The angle at which a direct view of the light sources in the luminaire is blocked

The process by which layers of materials are grown on a wafer-shaped substrate that is later cut up into LEDs is known as

epitaxial or epi growth

The terms "LED chip" and "LED package" mean the same thing.

False

Some manufacturers offer adjustable downlights that provide the option of changing the _______________ depending on the need in the space

Light distribution

Luminous Flux (power)

Lumen

Luminous intensity

Candela

A light source or luminaire typically has a single value representing its luminous intensity (candlepower).

False

The lumen rating of a light source expresses its total output without considering the human visual system; it is a sum of the radiant power across all wavelengths.

False

____________are used mainly for fluorescent lamps, __________________ are used for low-voltage halogen lamps, ___________are used for LED lamps

Ballasts, Transformers, Drivers

Standards like IES Illuminances are more than guidelines because they have been vetted by organizations like ANSI. Because they are a legal requirement, professionals must comply with them as good practice and for liability reasons.

False

The lighting quantities of illuminance and exitance both have units of lumens per area, with area in square feet or square meters. For both illuminance and exitance, the footcandle is used as theunit when the expression is lumens per square foot.

False

Track and track heads tend to be a static, inflexible system

False

Two of the primary types of LEDs used in architectural lighting are called AlInGaP (resulting in red, green, blue LEDs) and InGaN (resulting in yellow and white LEDs) based on the elements used in the LED materials.

False

While HID lamps are available in many different CCTs, they all have low CRI values of less than 70.

False

With low-pressure gas discharge lamps, the gas produces infrared energy and the phosphor then converts the infrared to visible light.

False

One of the IES TM-30 color rendering metrics measures how well a set of test colors under a light source match their appearance under a reference light source. This type of color metric is a measure of:

Fidelity

For the example where source 2 has lower intensity and the same size as source 1, what statement best describes the relationship of the luminance of source 2 compared to source 1?

The luminance of source 2 is less than the luminance of source 1

For the two light sources discussed which have the same intensity and size, but different spectrum, which statement best describes the relationship between the luminances?

The luminance of source 2 is the same as the luminance of source 1

A code once adopted by a state or at a local level is law that is enforced usually by a local building official also known as AHJ or 'Authority Having Jurisdiction'.

True

A cove typically directs light to the ceiling

True

A dual technology occupancy sensor combines both passive infrared and ultrasonic sensing technology.

True

A model code is a convenient way for local jurisdictions to arrive at well thought-out language that could be adopted as code.

True

Although red, green and blue LEDs have been around since the 1960s, they were not useful for general lighting until recently.

True

An IP rating for outdoor luminaires indicates how well a luminaire is protected for both solid objects and water penetration

True

Because they use low energy and can be powered by DC batteries, which in turn can be charged by solar panels, LEDs hold great promise for use in off-grid locations such as those in the developing world.

True

If the fidelity of a source is different from that of a reference source, meaning that the Rf value for that source is less than 100, it is possible that colors rendered under it would result in higher preference and better discrimination.

True

In the IES TM-30 system, the R(f) metric has a range of values from 0 to 100.

True

One main difference between fluorescent lamps and HID lamps is that the gas inside fluorescent lamps operates at low pressure while the gas inside HID lamps operates at high pressure.

True

The main difference between a high bay and a low bay luminaire is the light distribution

True

The spectral power distribution of light from a fluorescent lamp (the "colors" of light) is affectedby the mixture of phosphors used in the lamp.

True

The three types of light reflection from surfaces are defined as specular, semi-specular, and diffuse (matte).

True

The visible light from an LED happens when certain semiconductor materials create a larger drop in the electron's orbit. Manipulating the amount of electricity to change the drop can afford multicolored LEDs.

True

Troffers come in different 'flavors' such as a louvered troffer, a lensed troffer, and ______________ troffer

Volumetric

A luminaire that has about 50% of its light directed upward and about 50% of its light directed downward is known as having a semi-direct distribution.

false

Dimming systems in buildings provide convenience and aesthetics without changing the energy used by lighting.

false

The Building Area Method and the Space by Space Method are used to determine the power limit for lighting, and the two methods give exactly the same power limit.

false

The term "vacancy sensor" refers to an occupancy sensor that automatically turns lights on whenever someone enters a space.

false

Wall washing

lighting effect where a wall is illuminated such that surface irregularities are minimized (smoother)

Wall grazing

lighting effect where a wall with irregular surface is illuminated such that there are both highlighted and shaded areas (depth and texture)

Footcandles and lux are both units of illuminance. Which of the following best describes the quantity expressed by footcandles?

lumens per square foot

The candela (or candlepower) is the unit used for luminous intensity. Luminous intensity is a density that is best described by which of the following expressions?

lumens per steradian

Color preferences seem to be mostly affected by the saturation level of which hues?

red

The IES TM-30 color gamut metric R(g) expresses how a light source affects which aspects of the color appearance of objects?

saturation

Solid Angle (luminous intensity)

steradian (sr)

An LED combines two different semi-conductors. The "magic" happens at the interface betweenthose two materials. This interface is known as:

the P-N junction

The photons of light energy produced by an LED are the result of

the energy released by some electrons moving from high energy to a low energy state

A light source or luminaire typically has a single value representing its luminous power (lumens).

true

The term "control zone" refers to a group of luminaires that perform the same task and are controlled in unison.

true

Luminance

cd/m^2

The IES TM-30 color rendering method uses a set of how many test colors?

99

Spaces with high reflectance surfaces and a lot of inter-reflected light typically have a lot of contrast and can be very dramatic in terms of the lighting patterns.

False

Which of the following best describes how a fluorescent light source creates light?

Electricity energizes low pressure mercury vapor which in turn energizes a phosphor

A suspended luminaire is called that because it features a monopoint suspension

False

A wall is best illuminated with accent luminaires

False

According to the IES, the recommended illuminance for a kitchen counter with a critical task is 50 fc. This value in lux would be 5 lx.

False

Fluorescent lamps are economical, energy efficient and come in many CCTs . One of the main draw backs is that they don't last very long.

False

Similar to phosphor-converted LEDs, OLEDs use a narrow-band blue emitter layer with an external phosphor to make white light.

False

One of the IES TM-30 color rendering metrics measures how the color saturation of a set of testcolors shifts compared to their appearance under a reference light source. This type of colormetric is a measure of:

Gamut

If test colors under a light source appear to be more saturated than under the reference light source, the R(g) metric is

Greater than 100

HID stands for:

High intensity Discharge

Gas discharge lamps require extra equipment referred to in the video as "control gear." In the US, we call this the ballast. What are the two primary functions of the ballast?

Ignite (or start) the lamp and limit the current to the lamp.

Ultraviolet energy from a fluorescent lamp comes from which gas that is placed into the lamp?

Mercury

Which of the following factors affects the brightness of a light source but does not affect the luminance of a light source?

The adaptation level of the observer

Refraction is best defined as

The change in direction (or bending) of light as it passes from one material to another material.

The curve that is commonly called, "V-lambda," which is best described by which of the following?

The human visual response as a function of the wavelength of light

One of the problems with luminaires that are installed in-ground is

They can produce glare