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LIGHT |
What is it?
Light is a form of radiant energy. It is electromagnetic in nature and it is comprised
of wavelengths. Not all of these
wavelengths produce vision. Visible
light waves are the only electromagnetic waves we can see.
How is light
measured?
To measure the wavelength of solar energy, a
unit called the NANOMETER is used
Radiant Energy
What are three types of energy that the sun emits?
- Ultraviolet
- Visible Light
- Infrared
How is light interpreted?
Light is interpreted as color according to the
length of the light wave that hits the retina.
We see these waves as colors of the rainbow. Each color has a different wavelength. The human eye is blind to many wavelengths of
light.
Which end of the spectrum has the shortest
wavelength/ longest wavelength?
The blue-violet end has the shortest wavelength
whereas the red end of the spectrum has the longest wavelength.
What happens when all of the waves are seen
together?
We
see white light.
Seeing Using Visible Light
The cones, part of the external retina, are
receivers for visible light. The receptor cells of the retina allow us to see
in color. The sun is a natural source for visible light
waves. Our eyes see the reflection of sunlight
off the objects around us. The color of
objects we see, is the color of light reflected—all other colors are absorbed
What are the colors of
a rainbow? (in order)
ROYGBIV red, orange, yellow, green, blue, indigo,
violet
What type of
instruments do we use to help us see beyond our world?
Satellites and telescopes help us to see beyond our world.
Ultraviolet Radiation
Ultraviolet radiation is electromagnetic
radiation with a wavelength shorter than 400nm. It is the most dangerous part of the
spectrum to the eye. It contains the shortest
wavelengths in the spectrum. The shorter
the wavelength, the more biologically harmful the radiation will be. There are three categories of UV
radiation: UVA, B and C. They are broken down by their wavelengths.
w VA:
320-400nm—low doses over a long period of time can cause serious eye
damage
w UVB: 290-320nm—causes
sunburns
w UVC:
200-290nm—filtered out by the ozone layer
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