Science - Vision & Colour Flashcards
Visible light
Definition
Wavelengths ranging from 380nm to 780nm.
Light
definition
Visually perceived radiant energy, part of the electromagnetic spectrum.
Visible light is between what two parts of the electromagnetic spectrum .
Ultraviolet and infrared.
What colours corresponds to 380nm?
Blues
What colours correspond to around 500nm?
Greens
What colours correspond to around 600nm?
Oranges
Lumen
definition
Unit of measurement describing the quantity of light emitted from a source of light.
Watt
definition
Unit of power denoting the rate at which electricity is used.
Lumens per Watt (Efficany)
Definition
Measurement of how effective the light source is in turning the watts we put in into the light we want out.
Average Rated Life
Definition
Statistical way of determining how long lamps last before burning out.
What are the two classes of light receptors that the retina contains?
Rods and Cones.
How many cones does the human eye have?
About 8 million.
What are the cones in the human eye responsible for?
High-level daytime photo pic vision. Active in high light levels, responsible for colour vision.
How many types of cones does the human eye have.
Three
What is it called when one type of cone is missing or deficient?
Colour blindness
Rods:
- When do they operate?
- what type of vision are they responsible for?
Operate under very low light levels. Responsible for low-level night time vision (scotopic vision).
How many types of rods are there?
One
What do rods provide information on?
Only on the amount of light. Cannot provide info on colour.
Mesopic Range
Definition
Neither photopic nor scotopic. How we see under many typic outdoor nighttime conditions.
Light travels at what speed?
300,000km per second
aka: 186,000 miles per second
Does light behave as a wave or a particle?
Light can behave as both a wave or a particle.
Unit of measurement for light wavelengths.
Nanometers
Colours in daylight?
Mixture of all of the colours.
For white electric lighting, what mixture of colours are needed to produce white?
Red, Green, Blue
Spectral Power Distribution (SPD) Curve
Definition
Shows the precise colour output of a light source by charting energy levels at each wavelength.
Colour-Rendering Index (CRI)
definition
A number between 1 and 100 that describes the ability of a lamp to accurately render all the colour in a lighted space.
A good CRI might be anything over what number?
CRI 80+
Colour Temperature
definition
The absolute temperature of a blackbody radiator, having chromaticity equal to that of the source.
Correlated Colour Temperature (CCT)
Definition
Overall colour appearance of a lamp, measured in Kelvins (k).
Example of colour temperature of a warmer light source…
2700-3000K
Example of the colour temperature of a cooler light source, such as one that might be used in an office…
3500-4100K
Incandescent Lamp
definition
A lamp that produces light when it’s filament is heated by an electric current, causing it to glow/incandescent.
