NSF North Mississippi GK- 8 1 The Electromagnetic The Electromagnetic Spectrum Spectrum • Different wavelengths of EM waves. • These wavelengths of light and others make up a spectrum.
Apr 01, 2015
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The Electromagnetic The Electromagnetic SpectrumSpectrum
• Different wavelengths of EM waves.
• These wavelengths
of light and others make up a spectrum.
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On the Spectrum…On the Spectrum…
Left Side Right Side
Type of Wave
Wavelength
Frequency
Energy
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VISIBLE LIGHT
Electromagnetic waves we can see.
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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/wavereview.html
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How can I remember the seven colors of the visible
spectrum?
RROOYY GG BBIIVVED
RANGE
ELLOW
REEN
LUE
NDIGO
IOLET
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White LightWhite 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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ColourWe 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.
It absorbs all
the other
colors.
(OYGBIV)
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Sun’s R
ays (W
hite
Light)
Green Wavelength of
light
Absorbs all other colors
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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.
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Moving on to the HUMAN EYE
• You will now become blind.– You have 5 minutes to
figure out how you are going to take halfway organized notes on the back of your Color Notes sheet.
– Remember: these notes will be used on the test! They need to be legible!
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The The Human Human
EyeEye
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HA! Even if you’re peeking, you can’t see
anything!