Good Stuff Happens in 1:1 Meetings: Why you need them and how to do them well
Colors of Light Electromagnetic Spectrum
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The Electromagnetic Spectrum
• Different
wavelengths of EM
waves.
• These wavelengths
of light and others
make up a
spectrum.
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On the Spectrum…
Left Side Right Side
Type of Wave
Wavelength
Frequency
Energy
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Visible Spectrum
• The visible
spectrum contains
seven colors.
• Each of these
colors corresponds
with a particular
wavelength.
– Longest wavelength=
red light
– Shortest wavelength=
violet (purple) light http://ldt.stanford.edu/ldt1999/Students/tita/mjrproj/color/waverevie
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How can I remember the seven
colors of the visible spectrum?
ROY G BIV
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White Light
• White light is not a single color; it is
made up of a mixture of the seven
colors of the rainbow.
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Colour
We can
demonstrate
this by
splitting white
light with a
prism:
•This is how
rainbows are
formed: sunlight is
“split up” by
raindrops.
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Why do we see color?
• When our eyes see different
wavelengths of light in the visible
spectrum, we see colors.
http://www.astronomynotes.com/light/colorswvl.gif
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Seeing colour
– What we actually see is the light an
object reflects or in some cases the
light an object produces.
For example, a red book only reflects red light:
White
light
Only red light
is reflected
How do humans see color?
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Or…
• A red stoplight
appears green
because it
produces red light.
– It’s LUMINOUS!
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Seeing colour
– Absorption – the disappearance of an
electromagnetic wave into a medium.
• It’s the opposite of reflection!
White
light
Only red light
is reflected
The colors that don’t get
reflected, are absorbed.
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A white hat would reflect all seven colors:
A pair of purple pants would reflect purple light
(and red and blue, as purple is made up of red and blue):
Purple light
White
light
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Using coloured light
• What about an outfit?
White
light
Shorts look blue
Shirt looks red
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Black
• When you see black, all of the wavelengths
of light are absorbed and no light is
reflected back at you.
White
light
Nothing is
reflected.
All visible
light is
absorbed.
