color and light
DESCRIPTION
Color and Light. Intro question…. How is light different than normal waves??. What is light? Wave or Particle. Is light a wave? (ENERGY) Yes Is light a bunch of particles? (Matter) Yes Light is unique, it is what we call an Electromagnetic wave. How is light like a particle (matter)?. - PowerPoint PPT PresentationTRANSCRIPT
Color and LightColor and Light
Intro question…. How is light different than normal waves??
Intro question…. How is light different than normal waves??
What is light? Wave or Particle
What is light? Wave or ParticleIs light a wave? (ENERGY)
YesIs light a bunch of particles? (Matter)
YesLight is unique, it is what we call an
Electromagnetic wave
Is light a wave? (ENERGY)Yes
Is light a bunch of particles? (Matter)Yes
Light is unique, it is what we call an Electromagnetic wave
How is light like a particle (matter)?
How is light like a particle (matter)?Does not need a medium to travel through
Can travel through a vacuum
high energy (intensity of light) does not effect light the same way as normal wavesEnergy associated w/ frequency rather than
amplitude
Light consists of Photons- massless bundles of concentrated electromagnetic energy
Photoelectric effectEjection of electrons from certain metals when
exposed to certain frequencies of light
Does not need a medium to travel throughCan travel through a vacuum
high energy (intensity of light) does not effect light the same way as normal wavesEnergy associated w/ frequency rather than
amplitude
Light consists of Photons- massless bundles of concentrated electromagnetic energy
Photoelectric effectEjection of electrons from certain metals when
exposed to certain frequencies of light
How is light like a wave?How is light like a wave?Light can diffract (bend around stuff)Cannot travel through polar filtersCan exhibit Doppler Effect (change freq. Depending
on motion of source)
Can interfere (constructive or destructive) and refract (bend when travelling between diff. Media)
Has no mass
We refer to all of this as the dual nature of lightThis means………. Light is special
Light can diffract (bend around stuff)Cannot travel through polar filtersCan exhibit Doppler Effect (change freq. Depending
on motion of source)
Can interfere (constructive or destructive) and refract (bend when travelling between diff. Media)
Has no mass
We refer to all of this as the dual nature of lightThis means………. Light is special
Electromagnetic WavesElectromagnetic WavesLight is the oscillation of electric and
magnetic fieldsShake an elctircally charged rod then
you will create an EM waveMust always have same speed…
otherwise Electric Field and Mag. Field would reinformce each other to infinity or destroy each other
Light is the oscillation of electric and magnetic fields
Shake an elctircally charged rod then you will create an EM wave
Must always have same speed… otherwise Electric Field and Mag. Field would reinformce each other to infinity or destroy each other
Many diff. Kinds of “light”Many diff. Kinds of “light” A wide spectrum of types of light that we call
Electromagnetic Radiation These include…… infrared, radio, ultraviolet,
gamma rays, microwaves, x-rays, & visible light All exhibit same exact characteristics but vary
b/c of wavelength & frequency All types travel at the same speed
at The speed of light….300,000,000 m/s We can only ‘see’ the small portion that is ‘visible light’ The rest is invisible to the human eye
A wide spectrum of types of light that we call Electromagnetic Radiation
These include…… infrared, radio, ultraviolet, gamma rays, microwaves, x-rays, & visible light
All exhibit same exact characteristics but vary b/c of wavelength & frequency
All types travel at the same speedat The speed of light….300,000,000 m/s
We can only ‘see’ the small portion that is ‘visible light’ The rest is invisible to the human eye
Electromagnetic SpectrumElectromagnetic Spectrum
http://www.youtube.com/watch?v=i8caGm9Fmh0&list=PL09E558656CA5DF76&safe=active
http://www.youtube.com/watch?v=i8caGm9Fmh0&list=PL09E558656CA5DF76&safe=active
Visible LightVisible Light Wavelength range From about 700 nm to 400 nm 1 nm= 1 x 10^-9 m Different colors have different wavelengths &
frequencies Infinite amount of different colors ROYGBIV
Wavelength range From about 700 nm to 400 nm 1 nm= 1 x 10^-9 m Different colors have different wavelengths &
frequencies Infinite amount of different colors ROYGBIV
Absence of Light??Absence of Light??Black or White??White is combination of all colors
of lightBlack is complete lack of light, all
colors have been taken awayBlack would be the absence of
Light!!
Black or White??White is combination of all colors
of lightBlack is complete lack of light, all
colors have been taken awayBlack would be the absence of
Light!!
Transparent MaterialsTransparent MaterialsGlass- natural vibration frequency in the U-V
rangeProduces large amplitudes and energy is lost as
heat UV light cannot travel through glass
Visible light vibrates electrons w/ smaller amplitude so less collisions and less transfer as heat. So light will be reemitted as light Time delay between absorbtions and reemissions
causes light to move more slowly through glass than through a vacuum
Glass- natural vibration frequency in the U-V rangeProduces large amplitudes and energy is lost as
heat UV light cannot travel through glass
Visible light vibrates electrons w/ smaller amplitude so less collisions and less transfer as heat. So light will be reemitted as light Time delay between absorbtions and reemissions
causes light to move more slowly through glass than through a vacuum
Opaque MaterialsOpaque Materials Most materials there is no reemission, and light
Energy is converted to Heat Vibrations of the electrons are not passed from atom
to atom through the bulk of the material; rather the electrons vibrate for short periods of time and then reemit the energy as a reflected light wave
Metals are opaque- free electrons will vibrate easily and reflects light…. This is why metals are shiny
Most materials there is no reemission, and light Energy is converted to Heat
Vibrations of the electrons are not passed from atom to atom through the bulk of the material; rather the electrons vibrate for short periods of time and then reemit the energy as a reflected light wave
Metals are opaque- free electrons will vibrate easily and reflects light…. This is why metals are shiny
ShadowsShadowsShadows formed where light cannot reachSharp shadows- close light sourceBlurry shadows- fuzzy on the outside, more
dark on the insideUmbra- total ShadowPenumbra- partial shadow… some light
blocked but other light fills in
Shadows formed where light cannot reachSharp shadows- close light sourceBlurry shadows- fuzzy on the outside, more
dark on the insideUmbra- total ShadowPenumbra- partial shadow… some light
blocked but other light fills in
ShadowsShadows
Polarization of LightPolarization of Light Light waves are transverse Electrons vibrate and create a wave in the
direction of the vibration polarized
Since the electrons vibrate in random directions normal light is not polarized
If light shines on a polarizing filter, only the light waves in the direction of the polarization axis can get through
If two filters overlap at right angles, no light can get through
Light waves are transverse Electrons vibrate and create a wave in the
direction of the vibration polarized
Since the electrons vibrate in random directions normal light is not polarized
If light shines on a polarizing filter, only the light waves in the direction of the polarization axis can get through
If two filters overlap at right angles, no light can get through
DispersionDispersionDispersion--the breaking up of light into its component colors when travelling through a prism
Why does it happendifferent wavelengths (colors) of light travel through a medium
at different speeds, the amount of bending is different for different wavelengths.
Violet (short ) is bent the most and red(long ) the leastshort wavelengths travel more slowly (lower frequency) through
a medium than longer ones doits colors can be separated (dispersed)
by this difference in behavior.
Dispersion--the breaking up of light into its component colors when travelling through a prism
Why does it happendifferent wavelengths (colors) of light travel through a medium
at different speeds, the amount of bending is different for different wavelengths.
Violet (short ) is bent the most and red(long ) the leastshort wavelengths travel more slowly (lower frequency) through
a medium than longer ones doits colors can be separated (dispersed)
by this difference in behavior.
PrismsPrismsAny transparent substance that
can separate colorsRed bent least, violet most
Any transparent substance that can separate colors
Red bent least, violet most
RecompositionRecomposition
Opposite of dispersionCombining of colors of light using a
lens or mirrors to form white lightNewton’s Disk exhibits
recomposition
Series of mirrors
Opposite of dispersionCombining of colors of light using a
lens or mirrors to form white lightNewton’s Disk exhibits
recomposition
Series of mirrors
Newtons DiskNewtons DiskWhen spun fast enough
all the colors will turn white
Utililizes the principle of persistence of visionHuman eye retains an
image for 1/30th of a second
Connection… wheels on tvFiber optic blinker
When spun fast enough all the colors will turn white
Utililizes the principle of persistence of visionHuman eye retains an
image for 1/30th of a second
Connection… wheels on tvFiber optic blinker
How we see things….Subtractive Theory of Light
How we see things….Subtractive Theory of Light
Keep taking away colors until you wind up w/ oneObjects absorb every color other than the color it
appears However, most colors we see are various combinations
of colorsEx. A blue shirt may reflect mostly blue, some purple,
maybe some green, depending on the shade it appersWhat happens when light goes through filtersObjects we see act like light filtersColors combine the same way that pigments/paints do
Keep taking away colors until you wind up w/ oneObjects absorb every color other than the color it
appears However, most colors we see are various combinations
of colorsEx. A blue shirt may reflect mostly blue, some purple,
maybe some green, depending on the shade it appersWhat happens when light goes through filtersObjects we see act like light filtersColors combine the same way that pigments/paints do
Subtractive Theory of Light
Subtractive Theory of Light
Filters & PigmentsFilters & Pigments
Why are objects different colors?
Why are objects different colors?Is a certain object always going to be a
certain color no matter what??Depends on what kind of light is hitting it
Is a certain object always going to be a certain color no matter what??Depends on what kind of light is hitting it
Additive theory of lightAdditive theory of lightAdd colors of light to each other until
one is madeSimple adding of different colors of
light, no filters involved• Ex. TVs, • projectors
Add colors of light to each other until one is made
Simple adding of different colors of light, no filters involved
• Ex. TVs, • projectors
Why does white light look white?Why does white light look white?
Additive v. Subtractive Color MixingAdditive v. Subtractive Color Mixing
Subtractive Primary Colors• Cyan- reflects green & blue• Yellow - reflects red & green• Magenta – reflects red & blue
– So if you overlap a red filter w/ a blue filter you will wind up with Magenta
When different colored spotlights overlap in a dark
room, additive mixing occurs. If the commonly used additive
primary colors red, green, and blue all overlap in effectively equal mixture, white light is
produced at the center. Additive color mixing is
conceptually simpler than the subtractive color mixing you get with paints and pigments since you are just adding light energy in different ranges of
the visible spectrum.
Additive color mixing with red, blue, and green
additive primary colors.
Additive and Subtractive Color Mixing AnimationsAdditive and Subtractive Color Mixing Animations
http://www.physics-chemistry-interactive-flash-animation.com/optics_interactive/additive_color_model_mixing_synthesis.htm
http://www.physics-chemistry-interactive-flash-animation.com/optics_interactive/subtractive_color_model_mixing_synthesis.htm
• Art class color wheel??
Colors of ObjectsColors of Objects
http://www.physics-chemistry-interactive-flash-animation.com/optics_interactive/colours_of_objects.htm
Complementary Colors• Two colors that will combine to make white
light• Negative images
– Will show the original colors complement – Red & cyan, blue & yellow, green & magenta