Today’s Topics
-
Upload
kylynn-torres -
Category
Documents
-
view
21 -
download
0
description
Transcript of Today’s Topics
NSF North Mississippi GK-8 2
Today’s Topics
• Light– What is it?– Visible Spectrum
• Why do we see color?
• Why are objects specific colors?
http://priory.net/~fyamasaki/images/rainbow_sun.jpg
NSF North Mississippi GK-8 3
Why is light important?
• Almost everything in nature depends on light for life:– Plants use light to
make food as a byproduct oxygen is produced.
– Humans use light to see, make X-Rays, as electricity (solar energy), and many other things. http://home.howstuffworks.com/irrigation1.htm
NSF North Mississippi GK-8 4
What is Light?
• Light is a form of energy that sometimes behaves like waves.– All waves have a
wavelength which is the distance between one point on one wave and the same point on the next wave.
NSF North Mississippi GK-8 5
Wavelengths of Light
• Different wavelengths of light include radio waves, ultraviolet rays, and X-rays.
• These wavelengths of light and others make up a spectrum.
NSF North Mississippi GK-8 6
Visible Spectrum• Shorter wavelengths
have more energy than longer ones.
• Sunlight, which is the most important source of light, contains all of the electromagnetic spectrum.– Humans can only see
a small range of light called the visible spectrum.
NSF North Mississippi GK-8 7
Visible Spectrum• The visible spectrum
contains seven colors: violet, indigo, blue, green, yellow, orange, and red.
• The seven colors of the visible spectrum are the seven colors in a rainbow.
http://ldt.stanford.edu/ldt1999/Students/tita/mjrproj/color/wavereview.html
NSF North Mississippi GK-8 8
Colors in a Rainbow
• How can I remember the seven colors of the rainbow?
RROOYY GG BBIIVVED
RANGE
ELLOW
REEN
LUE
NDIGO
IOLET
NSF North Mississippi GK-8 9
Colors in a Rainbow
• Another way to remember: Make a sentence.– Example:
Rainbows Over Your Garden Bring Ideal Vegetables.
NSF North Mississippi GK-8 11
Why do we see color?
• When our eyes see different wavelengths of light in the visible spectrum, we see colors.
• How do humans see color? – What we actually see is the
light an object reflects or in some cases the light an object produces.
– Our eyes absorb the wavelengths of light in the visible spectrum. Then, turn these wavelengths into signals our brains can understand. The brain interrupts these signals as color images.
http
://ww
w.a
stronom
ynote
s.com
/light/
colo
rswvl.g
if
NSF North Mississippi GK-8 12
Why are objects a specific color?
• The grass appears green, because the leaves reflect green light. The leaves do not absorb (soak up) this wavelength of light and reflect it back (like a mirror), so we see the grass as green.
• On the other hand a green stoplight appears green because it produces green light.
NSF North Mississippi GK-8 13
Sun’s R
ays (W
hite
Light)
Green Wavelength of
light
Absorbs all other colors
NSF North Mississippi GK-8 14
White and Black Color
• White Color– When you see white, all of the
wavelengths of light (all colors) are being reflected back at you.
• Black Color– When you see black, all of the
wavelengths of light are absorbed and no light is reflected back at you.
NSF North Mississippi GK-8 15
Review• What is light?
– Light is a form of energy that sometimes behaves like waves.
• What is a wavelength?– Distance from crest to crest or trough
to trough.
NSF North Mississippi GK-8 16
Review• What are the colors of a rainbow?
RROOYY GG BBIIVVED
RANGE
ELLOW
REEN
LUE
NDIGO
IOLET
NSF North Mississippi GK-8 17
Review• Why do we see color?
– You see different wavelengths of light as color.
http://ldt.stanford.edu/ldt1999/Students/tita/mjrproj/color/wavereview.html
NSF North Mississippi GK-8 18
References• Barkstrom, Bruce R. August 18, 2005. What Wavelength
Goes With a Color?. 2005 August 18. <http://eosweb.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html>.
• Brown, Earle B. “Light.” The World Book Encyclopedia. 1986 ed.
• Gourdeau, Justine. November 3, 2003. Clouds and Particles: Basics – Rainbows. 2005 August 18. <http://www.atmosphere.mpg.de/enid/f962eee1b06705f8f51b4db2901f8668,55a304092d09/3__Sun_and_clouds/-_Rainbow_tj.html>.
• McGrath, Susan. Fun With Physics. Washington, D.C.: The National Geographic Society, 1986.
• Wyszecki, Gunter. “Color.” The World Book Encyclopedia. 1986 ed.