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Additive Colour Theory Artificial Sources of Light Natural Sources of Light Visible Light Colour Filters
Citation preview
Light is part of the electromagnetic
spectrum and travels in waves
Lesson #6, Section 3.3-3.4. Pages 221-229
Learner Outcomes I can evaluate, compare, and contrast
different artificial and natural light sources
I can describe how primary colours can be added to produce different colours and white light
ROY-G-BIV
Radiation is the wave like transfer of light from its source in all directions.
Light is often called radiant energy.
Light from the sun is formed by nuclear fusion.
Light is a form of energy When light reaches a surface, it can be absorbed and transformed into other types of energy.
… into electrical energy … into thermal energy … into chemical energy
The amount of energy a surface receives depends on
the intensity of the light.
The more intense the light, the more light can be
absorbed.
NATURAL LIGHT SOURCE ARTIFICIAL LIGHT SOURCE
Sun
Nuclear Fusion Thermal Energy Visible Light Energy
Incandescent (heat causing a filament of metal to glow - visible
light)
Electrical energy Thermal energy
Visible light energy
NATURAL LIGHT SOURCE ARTIFICIAL LIGHT SOURCE
Candles or Oil Lamps
Chemical energy Thermal Energy
Visible light energy
Florescent (ultraviolet light is absorbed by fabric
particles, which in turn emit some of the energy as
light - glowing)
Ultraviolet light Energy absorbed Visible light energy/particles energy
NATURAL LIGHT SOURCE ARTIFICIAL LIGHT SOURCE
Wood (fire)
Chemical energy Thermal Energy
Visible light energy
Phosphorescent (light energy is stored and
released later as visible light) paint
Chemical energy Visible light energy
NATURAL LIGHT SOURCE ARTIFICIAL LIGHT SOURCES
Bioluminescence (light produced by living organisms)
Chemical energy Visible light energy
Chemiluminescent (light energy released by
chemical reactions) glow sticks
Chemiluminescence
Movies (Shockwave/Flash)
Chemical energy Visible light energy
Incandescent light bulbs produce far more heat than light, or more infrared radiation than visible light energy. 95% heat vs. 5% light
Fluorescent bulbs are more efficient. 80% heat vs. 20% light
Read page 224 and complete this activity in groups of 3-5 people
Make sure you observe safety protocols
... evaluate, compare, and contrast different artificial and natural light sources?
#1. Explain how an incandescent light bulb works. ____________________________________________________________________________________
#2. Your watch dial may have glow in the dark numbers. Is this phosphorescence or fluorescence? Explain your answer. ________________________________________________________________________________________________________________________________________________________________________
#3. Why would a business choose fluorescent instead of incandescent lights? ____________________________________________________________________________________
#4. What is bioluminescence? Provide at least two examples. ______________________________________________________________________________________________________________________________
The various colors of the visible spectrum have slightly different wavelengths and refract by a slightly different amount.
The Primary colors of the visible spectrum are red, green and blue.
The Primary colors of the visible spectrum are red, green and blue.
Secondary colors are cyan, magenta and yellow.
The mixing of three colors of light to produce many different colors of light is called the theory of color addition.
Television puts the theory of color addition into practice.
By changing the brightness of the dots that make up the screen many different colors can be produced.
The television works by fooling the eye into seeing colors that are not really there.
The colour an object appears depends on the colours of light it reflects.
For example, a red book only reflects red light:
White
light
Only red light is reflected
A white hat would reflect all seven colours:
A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and blue):
Purple light
White
light
If we look at a coloured object in coloured light we see something
different
White
light
Shorts look blue
Shirt looks red
Filters can be used to “block” out different colours of light:
Red Filter
Magenta Filter
... describe how primary colours can be added to produce different colours and white light?
#1. What are the primary colours of light? How is white light produced? ________________________________________________________________________________________________________________________
#2. Explain how a prism can determine what white light is composed of? ________________________________________________________________________________
#3. You are a lighting technician in a theatre. The director asks for magenta light on stage, but you only have red, blue, and green lights. What could you do to produce magenta light? ________________________________________________________________________________________________________________________________________________________________________________________________________