What is it and how does it work
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a type of electromagnetic radiation of a
specific wavelength
Some of these wavelengths we can see
(visible light)
Some wavelengths we cannot see (x-rays,
infrared, ultraviolet)
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Light has characteristics of both waves and
particles
As a wave: light has an amplitude, frequency
and wavelength. Light waves can also
interfere with one another. Light can reflect,
refract and diffract just like other waves do
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Light has characteristics of both waves and
particles
As a particle: light bounces off surfaces in
random directions like particles would do
The particles of light are called photons
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Light scatters its energy as it moves away from
its energy source
Light scatters in all directions and fills up space.
That’s why a whole room can be lit up with on
light
Why is the sky blue? Blue light has the shortest
wavelength and scatters more than other light
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The brightness of light depends on the light’s
intensity
Intensity decreases and distance increases
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Light has a speed of 3 X 108 m/s (186,000
m/s)
Light will slow down as it passes through air,
water, and glass
material
Vacuum
Air
Water
Ethyl Alcohol
Fused Quartz
Whale Oil
n
1
1.0003
1.33
1.36
1.4585
1.460
material
Crown Glass
Salt
Asphalt
Heavy Flint Glass
Diamond
Lead
n
1.52
1.54
1.635
1.65
2.42
2.6
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More energy = higher frequency
Less energy = lower frequency
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EM spectrum consists of all energies,
wavelengths, and frequencies of light.
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Waves on the EM spectrum that we can see is
called visible light
Red, orange, yellow, green, blue, indigo,
violet (ROYGBIV)
But there are lots of waves on the spectrum
we cannot see like radio waves, infrared
waves, x-rays, etc.
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When light hits a surface, it will bounce off at
the same angle it hit the surface at.
Smooth surfaces – light rays bounce in the
same direction
Rough surfaces – light rays bounce off in
many directions
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Remember from the wave unit that when light
bounces off an object, it is known as
reflection
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When light is absorbed by an object, the
energy from the light is transformed into heat
energy
That’s why you feel warm when you’re
outside in the sun. Your body is absorbing
the light energy and changing it into heat!
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The color you see depends in the wavelength of
light that reaches your eyes
shorter wavelength = purple/blue = higher frequency
longer wavelength = red/orange = lower frequency
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The light from the sun contains all the
wavelengths of the colors we see
When the white light strikes an object all the
colors are absorbed by that object except for
the color we see. That color is reflected into
our eyes
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Most colors are a mixture of more than one
wavelength (color)
Primary colors – red, yellow, blue, mix
together to produce all the colors we can see
When all the colors of light combine we see
white
Black is the absence of light
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Remember when light enters a new medium
like air, water, or glass, the wave will bend.
This is called refraction
This is because the light slows down as is
passes through different mediums
Refraction makes objects appear like they are
in different positions
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When light hits a lens (like in your eye) the
wave will change direction
Convex Lenses- like in your eye- turn images
upside down
Concave Lenses
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https://www.youtube.com/watch?v=xkDhQG
XqwCM