visible light visible light is the light that our eyes can detect
TRANSCRIPT
Visible Light
Visible light is the light that our eyes can detect.
Light is…
A type of energy
Other types of energy are:
Heat, electricity, sound, chemical and …
Notes
Light is not …
The sunA globeA flourescent light
These are sources of light!!
Notes
Light is not ..
… necessarily made up of rays
This is just the model for light that we use to help us to predict what will happen is certain situations
Notes
Luminous Objects …
…produce light which allows us to see them. They are also called sources of light and can be categorised as:
Notes
•Incandescent sources•Fluorescent sources•Chemoluminescent sources•Bioluminescent sources
Incandescent sources…
...produce light from fast moving electrons that result from the heating a metal or gas
e.g.candles, light bulbs,
and the sun
Notes
Fluorescent sources…
…. fire electrons into gases causing the electrons in the gas atoms to jump to higher shells. When the electrons return to their normal shell they give off light.
Notes
Chemoluminescence
A form of energy
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Chemoluminescence
A form of energy
Notes
Bioluminescence Notes
What’s Your Theory?
If non Luminous objects don’t produce their own light, why can we see them at all angles irrespective of where the source is?
Notes
What the scientists say.
Virtually all objects have a rough surface when you look at them through a strong microscope. These rough surfaces reflect light at all angles.
We call this type of reflection Diffuse Reflection
Notes
What’s Your Theory?
Why do different objects appear to be different colours?
Notes
What the scientists say.
Light rays can have different energies and our eyes can detect the rays that have energies in the visible spectrum range.
Notes
Note !! infrared is shown as black
High EndLow End
White is not in the spectrum!
There is no such thing as white light.
White light is a result of all the colours of the rainbow being put together.
Light globes, fluorescent lights and the sun all appear to give us white light which actually means that they are producing all the colours of the rainbow mixed together.
Notes
Proof 1: PrismNotes
Proof 2: RainbowNotes
Proof 3: Newton’s Colour WheelNotes
Why do objects appear coloured? Coloured objects are usually non luminous so
they do not give off coloured light. Instead they absorb some colours and reflect
others. So a red object reflects red and absorbs the
other colours. Filters do the same thing e.g. a green filter
absorbs all the colours except green.
Notes
Colour Subtraction
http://mysite.verizon.net/vzeoacw1/colorsub.html
Notes
Cyan, Yellow and Magenta are known as the
Artists Primary Colours
What’s Your Theory?
How do the old TV screens give us coloured pictures?
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What the technicians say.
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What the technicians say.
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Colour Addition
http://mysite.verizon.net/vzeoacw1/coloradd.html
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Green, Blue and Red are known as the
Scientists Primary Colours
Comparing The Two SystemsNotes
What’s Your Theory?
Why do we see rainbows?
Where do we see rainbows?
Notes
What the scientists say.Notes
Where do we see rainbows?Notes