BU3 - Lighting Intro, Definition of Terms, Physics of Light

Luminous Flux

Measure of total perceived power of light

Lumen

SI Unit of Luminous Flux

Color Rendering Index

CRI stands for?

Color Rendering Index (CRI)

A quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source

100

CRI Range of Incandescent Light

Correlated Color Temperature

CCT Stands for?

A specification of the color apperance of the light emitted by a lamp, relating its color to the color of light from a reference source when heated to a particular temperature.

Correlated Color Temperature

Illuminance

Total amount of luminous flux on a surface, per unit area. It is a measure of how much the incident of light illuminates the surface.

Lux

SI Unit of Illuminance

Contrast

The difference in luminance or color that makes an object (or its representation in an image or display) distinguishable

True

True or False: Contrast is a fundamental element of interior design because it adds visual interest to a space that makes it striking and dynamic.

Glare

A phenomenon caused by extremely bright light sources or by strong brightness contrasts in the visual field.

Inverse Square Law

Light loses its brightness or luminosity as it moves away from the source.

Luminescence

Emission of light by certain materials when they are relatively cool ; The practical value of luminescent materials lies in their capacity to transform invisible forms of energy into visible light.

Fluorescence

Producing light from gaseous discharge

Phosphorescence

Organic fluorescent material which retains the radiant energy

Electroluminescence

Conversion of electric energy to light

Absorption

When a light beam passes through a transparent or transluscent medium

Reflection

The phenomenon in which light travelling in one medium, incident on the surface of another returns to the first medium

Specular Reflection

When any type of material has a polished surface, the light will be reflected at an angle equal to the angle of incidence

Diffuse Reflection

When the material has an unpolished surface, the reflected light is spread in all directions by multiple reflections on the unpolished surface

Spread Reflection

When the reflecting surface is not smooth, it spreads parallel rays into a cone of reflected rays

Compound Reflection

Reflector material that exhibit all the three types of reflection components to varying degrees

Transmission

When light falls upon a transparent material it is transmitted through it refracted (bent) as it enters the material, but emerges at the same angle that it entered.

Diffusion

Breaking up beam of light and the spreading of its rays in many direction by irregular reflection and refraction

Refraction

Change in the speed of light as it travels from one medium to another and there is a bending of the ray of light

Interference

Modification in the intensity of light due to redistribution of light energy in the region of two or more light waves

Diffraction

Bending light around small obstacles and hence its encroachment into the region of geometrical shadow